Hello, Goblin, and welcome to the msg board.
First off, I hope it didn't confuse you, but since this wasn't a proposal or presentation of new UT content, I moved the thread to the CEONSS forum where all such server-related topics are expected to be found.
About the map suggestions now, as a first, more general comment, I can tell you that when it comes to roster changes and specific map removals or additions, there are several factors besides popularity and personal preference that affect those decisions. Gameplay quality (actual gametype-adherence, playstyle plurality, geometry/terrain design, vec & weap loadout balance, z-axis usage, known glitches n' exploits), existence of known server-destabilizing bugs, server resource (CPU, net) drain, filesize and assorted file trail, aesthetic choices and various other considerations all come into play and can affect the outcome of such a review and even countermand a vote of public preference. While I'm not heinz and cannot for certain tell you what his exact thought process was that lead him to exclude any of the maps you list, I believe I have enough insight on each of these cases to safely hazard an educated guess as to why they're not on CEONSS. Also, do keep in mind that unquantifiable aspects such as "fun" radically vary from person to person and, thus, aren't easy to embed into a decision-making process that would speak to an entire community's collective taste. Also, also, we're not TechCom, so... there's that too

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ONS-CataldiPark-EONS-Edition-V1
You may've not played it in awhile and forgotten most of its... peculiarities, but to some of us, myself unfortunately included, they've become too deeply ingrained to forget. Other than its entirely average terrain, vec loadout and node link setup arrangement, Cataldi has nothing else going for it. On the other hand, every aesthetic element its mapper included seems to've been made with the singular intent to annoy and aggravate the player as much as humanly possible. You can turn the completely unfitting background music off, but you can't escape from the disembodied shrill screams echoing all across the playground-themed environment, the random dog barks, bicycle ringings or any of its other recorded charms; if I remember correctly, a previous version even had random whales plummeting from the sky in the background, Hitchhiker's Guide to the Galaxy style - guess the map matured enough to shed
that excess :rolleyes:. At any rate, I could swear that prolonged exposure to this map's environment was almost scientifically designed to push ppl towards infanticide. The net-enabled karma bounce balls consume resources without even contributing anything to gameplay (unlike with MasterShower's ducky) and the stylings of this map's static meshes - buckets, shovels, slingshots, glitchy plastic ramps n' all - don't help its legitimacy's case much either. All in all, its gameplay is dead average and ppl's senses have to suffer the stimulus onslaught for the entire length of a match there to get just that as a payoff, so its absence from almost every popular ONS(Plus) server shouldn't be much of a riddle to anyone. In fact, you're the first person I've ever come across in my entire UT life to've made a positive mention of this map, much less a plea for its return. I wouldn't hold my breath for heinz to add this one to the roster, but then again, considering this is your first post too, I can't help wonder whether someone's punking me :/...
ONS-2Tricky-DW-RC2-Edit1
The map has chokepoint primaries for a total of 5 nodes laid around a terrain that's less suited for warfare and more for stunting. I get that nitro boosting EONS scorps + CEONSS' air control mutator makes for daredevil funsies, but personally, I don't recall ever having a gg there. Still, it was average enough to've been hosted on this server for quite a while, but I dunno what compelling case anyone could put forth to defend its place in the roster. Considering you're clamoring for the standard cars "wo staff" version too, you wouldn't be able to enjoy even its stunting silliness, so what does that leave?
ONS-2nd-Raceway-DW-RC1
This one has enough strategic depth to make its gameplay decent enough, what with the coordinated garage raids n' all and that's why it's been on the server for about as long as 2Tricky, IIRC. It was probly removed in some kinda reshuffling, but I suspect it can return. I can't think of any map that puts WailofSuicide's EONS vecs to better, concerted use than this one either.
ONS-Battlefront-Rilez-ECE-32p-v6
Umm, I dunno how exactly you came to the conclusion that this map was as popular as "Torlan in its time", but from what I remember playing it on TechCom, it was pretty much the embodiment of a chokepoint node design's cautionary tale. If 2Tricky's return is tenuous by virtue of its chokepoint primaries, the fact that this map wasted most of players' regulation time at failed attempts to turn the bunker chokepoint nodes - 2 of them - should logically make its prospects for renewed hosting both impossible and horrifying to most ONS regulars. To better illustrate why chokepoints are such a serious detriment to ONS gameplay quality, take a look at the following pic:

- Battlefront-Rilez-ECE-32p-v6_ONS_area_brkdown.png (158.71 KiB) Viewed 16474 times
You'll recognize it for a clear top-down view of that map's terrain. You'll notice outlined in green its available actual play area, but also a number of yellow and red marked areas. Depending on a match's progress, the action and the, umm, battlefront, will shift from one of these coloured territories to an adjacent one with opposing teams starting right outside 'em and heading in for their contested nodes. Difference is, while in the case of the yellow areas there's some meaningful choice as to where to go and how to approach the fight (the very essence of ONS), in the red ones the action gets bogged down around the only node available, thus kneecapping gameflow and effectively
changing the gametype from ONS to a 1-lane MOBA styled game without heroes. This kills ONS and is the reason most ppl are averse to chokepoint featuring maps. Since this one has two of 'em, here's some simple math to explain how the problem compounds:
Green (playable area): 348x180 = 62640px
Yellow (ONS area): 119x162 (19278) + 45x139 (6255) + 125x157 (19625) = 45158px (72%)
Red (non-ONS area): 94x172 (16168) + 88x173 (15224) = 31392px (
50.1%)
What that last figure means is, more than half of the map's terrain in total can prove to be non-conducive to the entitled gametype. Understanding that as a server admin, I think anyone's decision would be pretty straightforward from there, no matter how much anyone might compare it to Torlan.
ONS-UP-OperaHouse
I'll agree that OperaHouse is fun and it's been on the server for lengthy intervals as well. That said, it's kinda haggard, both in its appearance (colour palette) as well as its geometry (all those angled, jutting supposed building debris). There's room for tactics and maybe even for some strategy, but I guess the constant mining and sniping has taken a toll on its popularity over time, esp. when it's held up against more successful thematic/gameplay peers such as Spiffingrad (which also has vecs). I'd call it a tossup on whether this one returns, but heinz would need to tell you for sure. Btw, a map having vehicles doesn't preclude dueling funtimes from taking place; consider, for example, maps like MasterBath, Tyrant, the non-NV Maelstrom, VK's-Playground (has mantas), BitchSlap, TripleSlap, Cap'nGordon'sBoP, ChainIsles (1 and 2), Gunshop, Dreamus2, Katharos or StarReach.
PS: I'd agree that Acerbus and MBB_WO are pretty much ho-hum affairs (there's plenty more to add to that group too), but by what reasoning does StarReach or OmahaBeach belong in that group, much less deserve the "crap" label? The only thing I'll bother to debunk until you offer at least one actual argument that supports this is that they supposedly are server clearers. That claim is patently wrong considering that for years on end both those maps would (and did) fill servers to capacity here and across the pond and, as far as I bothered to check for StarReach just a while ago, its average player numbers are nothing like you describe. Is hearsay all you're basing this on?
Anyway, sorry to've come down hard like that on your first visit; it's just that undue map critique is kind of a sore point for me. Again, welcome to the msg board and plz do keep providing feedback on the roster's quality, every bit helps

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