SE just doesn't do innovation sadly. With skilled class designers and a dedicated healer designer even a melee healer might be possible, but the current team just isn't capable of it.

This is why they just scrapped Chemist entirely, because it required being creative and we got a recycled SCH clone with flashy visuals instead. Even Reaper is just a mish-mash of various other jobs and the same formula shuffled about a bit to feel different, with flashy animations.