In regards to the tunnel-vision argument.

For every single wipe that I've had because a healer was dpsing instead of healing I have also had a wipe where the healer was doing nothing else but heal, except the only heals they were using was Cure (or the equally useless equivalent on AST & SCH) and Medica 2.

What do we do about that? Reduce the amount of heal spells to "big single-target heal" and "big aoe heal" so those types of players can't tunnel-vision the wrong spells? Make healers auto cast because some people can't be bothered to use more than 2 buttons?