The change to healers in the new PvP seemed necessary to ensure that Crystalline Conflict isn't made lopsided for teams with a discrepancy of healers. While this has naturally bled over to affect Frontlines, I don't think this is a bad thing. I'm old enough to remember full 24 alliances queued up and waiting at the spawn with 1-0 healers across the team. While you absolutely could win without healers, that was only when the vast majority of the team knew their s*** (rare) or through scoring off of objectives and not being focused by either team most of the match (not as rare, but uncommon).

Without dedicated healing roles, now every person has several self-heals and a "full-HP/MP" button with a 5-second casting time (you'll be miles ahead of the average player just by acknowledging this skill's existence), players have more self-agency than ever to keep themselves alive than ever before. No person should be able to be kept alive through an onslaught of half-a-dozen or more people because a distant person's heals negates nearly everything that was done in the last 10 seconds. Spot-heals are fine if someone needs a few more seconds to run to safety (and not trailed by a dozen people), which is what WHM and AST still can do.

With the current pvp kit you are just another dps but with a weak single player heal every 15 seconds and a dmg ability every 15 seconds. It feels so boring and simple to play compared to what it used to be, and while this issue is the same with every job, healers suffer from it more.
Hard disagree. None of the "healers" are just another dps with a weak 1-button spam. AST is a hybrid of support, AoE pressure/burst, and interference. WHM has burst, interference and kill set-ups just by the existence of Miracle, support and one of the most useful and well-rounded LBs in Frontlines that charges quickly. SCH naturally is mostly support, but can buff the damage of all nearby teammates / DoT and debuff an insane amount of people at once (which will build up many assists if your team doesn't suck), and the ability to apply a shield on their whole party can be clutch if their party isn't attentive of SAMs baiting with Chiten. SGE unfortunately is probably the most handicapped healer in Frontlines, as their effectiveness is reduced if they can't be near point-blank (which is basically an invitation to get dogpiled for not having a 60% defense bonus) to use their most effective DPS skills, otherwise they're really only useful for applying short defense debuffs, limited shielding and dropping an incredibly situational LB.

Heck, getting Battle High 5 has never been easier on healer than it has been after the PvP rework.