With vgood c-elf agility stealth was trash at advanced. I think maybe we just have different ideas about what constitutes trash. I'd guess that about 20-25% of the time, hide still abjectly failed. Most of the time it didn't work against any primary guild with 'scan.' Running tests against NPCs, I could sneak+hide maybe 2 or 3 rooms about 75% of the time, but farther than that the success rate dropped off dramatically.
Again, this is opposite of my experience. Very opposite. Elven agility has stymied my progress past advanced constantly. So I think you're projecting numbers that aren't there.
At any rate, I think the reason that they don't open it up is because the JP don't have any reason for being, so it eventually devolves into power-struggle griefing. A couple of c-elf assassins with decent stats at peak time can be so completely dominant in the 'rinth that it essentially takes Staff intervention to restore balance.
This power-struggle griefing is what I call the struggle for relevance, and it occurs to almost every clan in the game (albeit the 'rinth is where it turns into violence more readily). All 'rinth groups end up suffering through it, the difference being that only one of them is static and thus survives every conflict, and that is actually what's led to a serious, perpetual imbalance there over a long period of time that is not reflective of the 'rinthi world.
I don't demand the Jaxa Pah back, though I disagree that they have no reason to be there. By the standard you're setting, only one group should ever be doing one thing (which is anti-conflict), or they should all be equally not there because their role is arbitrarily made. I do, however, think city elf presence is something that needs to be acknowledged as a very large part of the in-city world. Currently, as whitt noted, it is purely a pariah race to all, rather than just an oppressed race by the state, and keeps all the anti-clan rules and conventions from a time when city-elf clans were active.
*shrug*
We can go back-and-forth about what we experienced in-game all day without resolving anything. So...whatever. For what it's worth, I'm so thoroughly convinced that I'd never roll a stealth extended subguild without having a stealth primary to piggyback on. At any rate, I highly doubt you -honestly- had trouble getting past advanced, because I've played a whooooole lot of city-elf assassins over the years, and they all branched from sneak and hide within 5 or 6 days. So I mean...unless something has changed dramatically in the last several years since I've played one, I'm not sure what to tell you.
As to the rest: the Jaxa Pah is just there because it's there. I'm not really condemning that. Personally, I'd be fine with opening it merely as a flavor role--to allow players to play a role that fills in a part of the game's universe, regardless of whether it's arbirtrary or not (everything in a fantasy world is purely arbitrary, if you want to get reductionist about it), other things being equal. Unfortunately,
ceteris paribus doesn't apply, because it only takes a few active JP to completely change 'rinth dynamics.
My personal guess about Staff discussions is that city-elves statistically are so good at miscellaneous griefing that giving them a safe space in close proximity to the places where the griefing occurs contributes vastly more to negative than positive experiences in terms of playerbase satisfaction. When you combine excellence at miscellaneous griefing with having nothing organic to do...griefing becomes the default. People start getting pickpocketed or burglarized for no other reason than ¯\_(ツ)_/¯. I'm not being hypocritical here: I freely admit that I engaged in the same behavior, because it takes a huge amount of self-control not to engage in it as a young adult. Rash had AI agility as a pickpocket, and I kept on mercilessly stealing people's shit even with 20k sitting in the bank, just because I could. And sure, there are a lot of things in the game that get done for no better reason than that, but there are very few such things that actively enrage most players. Nobody cares if you generate 20,000 'sid from scrab leg sales. If you generate 20,000 from stealing people's back-up knives and mount tickets, it will kick off IC and OOC crusades. And sure, human pickpockets and burglars can be pretty good, but there isn't a single human clan in the game where, if you get caught picking pockets or locks, they'll give you a big ol' clap on the back and a "well done," so you have to meticulously plan and target heists, or eventually your nuts will get crushed. With the JP, that counterbalance doesn't exist until your shenanigans get so outrageous that someone on Staff gives you a permanent crimflag (I didn't get one until I stole Samos's keyring and magick sword). So: on the one hand, I can make an argument that I, myself, probably would no longer abuse the privilege, because I'm 36 years old, with 18 years into the game, so maturity and experience (usually) give me a good idea of where to draw the line; on the other hand, I also know what that sort of blank check leads to when you -don't- have maturity and experience.
I agree with you that the typical state of affairs in the 'rinth is not accurately represented without the JP being open. However, until there is some sort of effective balance--which would, I believe, be facilitated by giving them a reason for being beyond "we're here, we have long ears, get used to it"--the game probably is better off without them being open. The 'rinth certainly is not any fun when the East and West have "gone to the mattresses" and any noob PC who rolls into the 'rinth without access to a clan safehouse gets mercilessly ganked for no other reason other than they -might- be recruited for the other side.
That being said, a "reason for being" probably isn't sufficient to balance griefing vs. satisfaction in a stable equilibrium. There also needs to be some set of rules or documentation regarding appropriate JP behavior, and there needs to be a set of known and predictable consequences for that behavior, so punishment can't simply be dismissed as "Staff favoritism." Until that happens, I doubt anyone on the Staff team wants to take on the burden of dealing with all the miscellaneous bitching that a crew of elves with a safehouse inside the city is inevitably going to gin up.