PVP as we all know has its fair share of flaws, but I believe some just make the subgenre of FFXIV unplayable. While it would be commonplace to assume that each class would have it's own unique way to keep it viable in this game mode that's far from the truth. Classes like Reaper and Summoner are much MUCH more powerful in terms of combat, having many advantages over the other classes. One of said advantages is the ability to sustain themselves in combat without heavily relying on the widespread Recuperate ability that regenerates HP at a cost of MP with the use of: lifesteal, protective barriers that when broken heal the user, etc. While you may think "Why not just play these classes?" some people don't play these classes or just have preference in the main game and would like to continue playing as their job that they've spent so long levelling and getting into the story of. One way that we can change this is by giving each class a way to sustain itself, for example, though GNB has 3 types of junctions (each with their own specific way to change up gameplay in PVP) it is near impossible to find anyone in a 1 on 1 duel who uses anything except a DPS, which limits your ability to sustain yourself as you only have damage output. This would be okay if this damage output was good enough to not be negated by a single Recuperate ability. One way this can be changed (in GNB's sense) would be to give it it's "Brutal Shell" passive ability back, that way it can have survivability even in this DPS junction, or any junction for that matter. I feel many other classes fall short of this, falling victim to not being able to sustain themselves in combat or keep up with the survivability of the "Meta" classes in PVP. If PVP does not provide any balancing to help with these issues PVP will continue to be a chore for many players when they have to play it. I hope this was comprehensible and I mean no disrespect to the team at Square Enix, I just feel that in order to make the PVP game mode a little more accessible some changes need to be made, Thanks.
EDIT: I am a GNB main and I do have bias to this class as I love it's story and gameplay, but I have played many other classes in PVP and most still fall short survivability wise.