I always laugh when people imply PvP isn't popular in Final Fantasy. Sure the series is historically an RPG (rather than an RTS which is vaguely PvP), but this game is also an MMO, and any MMO is going to have a demand for PvP.
Wolves Den and Frontlines were plenty popular at their launches, and matches are still possible if you can stomach the wait. It isn't dead content, just frustrating to get into due to the queues. PvP in ARR is popular enough for the developers to even waste time on it, otherwise we wouldn't have Slaughter (and oh how I wish we didn't, but that's a rant for later) nor the new rules and zone in Heavensward, though that really isn't what they should be doing for PvP at the moment...
The issue with PvP in ARR is one of creating a steady playerbase. The current situation is one where people stop queuing after a while, either to take a break from it or to do other things, and that creates a negative feedback loop on the queues. Less people queue, queues take longer, people see long queues and don't queue, thus queue times get longer. That's the biggest issue with PvP in this game, for some reason SE insists on adding more modes which just splits up the PvP community, making the problem worse. It's mind boggling, made all the more frustrating by their out right refusal to even communicate with the PvP community (at all? I don't recall them ever gracing the concerns of the PvP section with a response).
Kind of hilarious considering they got PvP so right in the Gold Saucer. Say what you will about the Triple Triad Tournaments, at least it gets people playing the game on a regular basis, and Chocobo Racing completely skips the issue by having NPCs fill the ranks. I'm sure nobody wants to PvP to play with NPCs (I certainly don't, the PvE at mid is annoying enough), but it could have a dramatic impact on the queue timers for Wolves Den; You queue, get in instantly with NPC allies enemies and the odd PC, which sucks for PvP but at least it is easy farming, thus more people queue for Wolves Den and as such you end up playing against more PCs than NPCs. Both Wolves Den and Frontlines would also benefit dramatically from server side scheduling, you'd know that the people who are interested would be queuing at a certain time and that would improve queue times. Rather than the ridiculously drawn out Triple Triad Tournament timetable we got (really? A whole week for one Tournament and then a week of nothing? Sigh), PvP would probably benefit more from "You get extra rewards for an hour at this time, and this time, etc. etc.". Split the day into 8 three hour slots, with one of those hours being better rewards and the other two being cooldown? Speaking of rewards, outside Glamour they really could do with something worthwhile, you know, for those of you who can't buy i70 gear and desynth it for a tidy sum. Always figured it would be nice if that Materia Merchant at the pier would sell all the combat materia, fairly ridiculous prices for the IVs to limit the impact on the economy of course but how effective would that be? Spiritbond for materia or PvP? I know what I'd pick, every. single. time.
Are they doing any of that though? Nope. Instead we're getting a new map that's probably as bad as Slaughter... Yay... I wouldn't even call any of that particularly difficult to produce, given much of the framework is already in place. Duels certainly aren't something that should be difficult to implement, and duels would pretty much completely avoid any queue issues so that would be able to satisfy PvPers for a good while, hopefully while someone is slapping people over the head going "Stop work on this new Frontlines mode and do all this instead". Mark my words, that new map is just going to be an exact repeat of Slaughter unless SE actually addresses the real issue with PvP. I wouldn't even mind Slaughter and the new map if we had duels, because I could duel while I wait for them to fix the twisted wreckage that is Wolves Den and Frontlines.
Seriously SE, give us duels at the very least. Same rules as Triple Triad, limit where we can, or just shove a 1v1 mode in Wolves Den that two people can party up and queue for. It would be a very simple addition that would keep people satisfied with PvP while you keep delaying fixing the actual issues to add more Frontlines maps...