One of the problems is just the available ninjas we have. Heavy control teams that can layer debuffs or lots of mass ignite are helpful, but most of the ninjas that can do that are rare (Susanoo Itachi/Ninetails Naruto) or otherwise lackluster (Deidara).

Some of those proposed changes would make the healer teams basically useless. It's easy to perceive them to be really strong when watching them because of how they can get back to full health/end fights at full health, but they're often riding a fine line between victory and defeat. If just one of them ever goes down, it usually means game over. It's just a different playstyle than most teams that people need to adjust to.