This isn't about class balance which is a whole different problem in itself. FFXIV's pvp is the most boring experiences out of all the MMO's I have played. the developers need to look into how other games do their pvp and use what works.
General problems
1. progression
PvP has no ranking system and gear was changed to have no stats. All stats were equalized in order to give all players an equal chance. Ranks should give titles, unique items, consumables etc. the point of ranks should be something to show off as much as unique items and titles you get from savage raids. if PvP gets popular you can even use it for matchmaking.
2. gear
there needs to be something to work for and pvp gear just being for glamour is enticing but its needs to be more. Bring back unique stats for pvp. These stats will make it so you can survive in pvp longer and deal more damage. pve gear should not effect pvp in anyway so someone coming in with savage gear shouldn't be on par with a fully geared pvper. when players have pvp sets the combat should be more equalized. This gear should not be locked behind ranked and essentially be the pvp version of gearing with tomestones for pve.
Frontline problems
1. Teams
My biggest problem with pvp ever since I started playing in 2.0. Teams need to be 1v1, and players need to be lowered down to about 16 per team. 24 players in a 72 player match makes my job feel like i'm pissing in an ocean. It is hard to keep track of anything i'm doing, and there is no teamwork. 1v1v1 teams is a huge problem where it makes every loss feel unfair and makes every win feel not deserved. pvp is a test of skill and throwing a wild card uncontrollable 3rd team is frustrating.
2. Maps
Almost all maps in frontlines are these giant open spaces with ramps that lead to platforms. The objectives are always an iteration of "stand in the location". This may be another problems of how large teams are but with 1v1 teams of 16 players each, this can be changed. Give us simplified modes such as capture the flag, capture points, attack and defend etc. maps that are multilevel and classes having various ways of travel is the most enjoyable and well designed maps i have played such as SWTOR's maps.
Feast problems
1. team compositions
without thinking of class balance, feast needs to be more open on team compositions and have 2v2 mode, 3v3 mode and 4v4 mode. As of now it's too constrained how the developers want you to play. another problem is the queues die shortly after the first weeks after a new season starts because rank decay doesn't exist.
PvP and PvE should be separate entities and it's a good choice to make sure combat is balanced differently. When PvP is popular it grows its own community and will cause queue times to be faster. but until then we can only play in prime time and in a very constrained boring format. I never ever write things like this so thanks for coming to my TED talk. Thank you.