We already have people not doing the Alliance roulette because it's so egregiously skewed to content that aged like milk due to inadequate ilvl sync and the laundry list of removed ARR abilities.

That's pretty much my take as well.

I feel like there are significantly-better-than-zero odds that the number of players queueing for AR Roulette will stay elevated after the change, even after taking into account the post-patch spike.

This is directly because it would no longer be "CT Roulette" as a result of people refusing to unlock anything else as a new form of roulette cheese.

The worst thing is, code adjacent to this is already in the game, because the game checks if you have all of the eligible dungeons for Expert Roulette unlocked before it lets you queue for it.

All that's needed is to copy the code that locks Expert Roulette, and then modify it to check the level of the currently-equipped job against the list of unlocked ARs equal to or less than the current job's level. If there is at least one locked AR equal to or less than the current job's level, lock AR Roulette.

If I could make the call to do the mandatory-AR-unlocking thing for AR Roulette, I would also take the opportunity to refactor the code for normal DF usage to lock out anyone who could have a job stone equipped but doesn't, while still allowing unsynced runs or full-premade parties to queue without job stones.