As a sort-of new player (6 months now I think?), I just want to add that GC restrictions are the last thing that has kept me out of PvP. I'm not arguing that it may be the ultimate limiting factor for experienced players, but I've encountered many more obstacles.

Basically I think PvP is way too inaccessible in FFXIV, here is a brief freethink of all the reasons I've been playing 6+ months and only just now even considered PvP (and only because I wanted an Axe for PvE sold for PvP points).

I learned Frontlines exist last week.
That's 6+ months of playing and I never even came across information that FFXIV has Battlegrounds. It's buried behind reaching L50, completing a totally-unrelated quest (Pup No Longer, which I never completed, because I had no interest in Deathmatch PvP while still learning how to tank Brayflox Story), and then hidden behind a generic quest symbol at my GC headquarters (I don't hang out in Ul'dah much).

In other worlds I've played, I'm encouraged to get into casual Battleground PvP from about Level ... 10? maybe?
It's introduced in a gentle, carefree way while I still have a tiny ability set and it's easy to jump in and try things. This is the same reason early dungeons like Sastasha exist — it gets people comfortable with the ideas early on. Restricting PvP until Level 50 is like making someone's first dungeon Aurum Vale, then being surprised they don't ever want to do dungeons again.

I'm not bribed into PvP.
Developers need to understand, most average players of worlds like Eorzea are not 'gamers' the way developers usually are. They don't want to do something with potential ego-deflating consequences just for the challenge. That's why they enjoy PvE, it constantly pats you on the head and tells you how amazing you are and doesn't let you lose (not intended as cynicism — this is part of what makes questing adventures fun). Propose getting torn apart in PvP by master players — which is stressful, not fun — and it's like: "What do I get out of it?" Note the Relic grinds, for example; players will do a lot of things if you bribe them sufficiently.

Something as simple as opening up Frontlines at level, say, 20? And including a 'PvP Roulette' with Leveling XP + GC Seals alongside the 'Leveling Roulette' would bribe newer and alt players into trying PvP — creating a more casual crowd to draw from and populate the Unrated content with.

Why is bribery and early accessibility important?
Because while some players will simply never have any interest in a competitive/unpredictable environment, other players (like me) are just either oblivious, intimidated, or both. It took my i205 Axe to motivate me to start poking around for Wolf Mark options, and after initially being filled with absolute dread, I realized Eorzean PvP is... actually kind of fun, and not everyone who PvPs is a salt-filled cyclops that hates you (in fact, most of them are fairly nice).

Right now, FFXIV makes the player work for PvP:
"Okay, Warrior of Light. We have hidden PvP somewhere in Eorzea. We won't tell you where. If you discover it, you may have to keep searching to find the other unlocks. Your incentive for doing it is... well, there isn't one, really. Also, most of your queues will never pop — there will be no explanation for this. If you give up after waiting in queue for 3 hours, that just means you're weak!"

"Oh! Also, there a million tiny rules about PvP that are completely different than PvE. There will be no explanation of this anywhere. You must comb Forums and Wikis to learn about odd things like ranged damage scaling on BRD/MCH, and then you must also hope that Wiki was updated to account for patch changes and whether or not these modifications apply to Frontlines, Wolves Den, or both. Also, here's some PvP abilities! (what?) Have fun!"

And then it's not very surprising most players either never learn it exists (me) or give up in short order and forget it exists.

"But FFXIV makes the player work for everything, including PvE!"
Yes, but this is fine for PvE because PvE is relaxing and fun. I'm willing to be filled with mystery and slooooowly unlock things in PvE, because that feels like a standard single-player RPG progression through the world.

This works poorly for PvP, because the matches themselves are the motivation, not the 'discovery' that it exists. It's a different mindset, and a different type of player. If you bury PvP at L50 and behind quest unlocks and other loopy convolutions, you're pushing away the crowd that would be most likely to populate it.

Or, put another unfortunately-blunt way: PvP doesn't care why everyone is killing subduing each other. I care, because I'm a lore/story nerd, but I'm the minority here and I don't think the average PvP audience does. They would much rather jump in with no explanation and start slaughtering Lalafells, than wait 50 levels and half the MSQ just to have better story context.

(This is in direct contrast to PvE, where FFXIV's insistence on plot cohesiveness and world-logic has made it the most satisfying persistent world I've participated in.)