I'd love to have something simple that makes me press something else than 1 all day. It doesn't even have to be complex, it could be something like...

WHM - Proc system similar to DNC/RDM
Example: Spell 1 has a 50% chance to unlock Spell 2, which has a 50% chance to unlock Spell 3. For extra fun, Spell 2 and 3 could have a small aoe effect on top of their single target damage.

SCH - Multiple dots with different total potencies, cast times and durations, one of them being an aoe, and a Thundercloud-like passive
Ex: Single target 18 and 30s dots + aoe 24s dot. On each tick, each dot has a 5% chance to proc SCH!Thundercloud, allowing the player to instantly cast the dot that procced with increased base damage and without overwriting the original dot.

AST - Spells and dot procs have a chance to slightly shorten Draw timer
Ex: Each GCD cast and Combust proc have a 10% chance to reduce Draw CD by 5s.


Bam, all healers have a different offensive gameplay, and without even creating new assets! WHM could use Stone 3, 4 and Glare; and SCH could use Bio I, II, Biolysis or Miasma. All it would require is a few passives here and there.

Hell, those changes could even make for different gameplay as we level up!
WHM could start with Stone, add Stone 2 procs later on, upgrade them to 3 and 4 during the 50-70 levels, and then add Glare at level 72.
SCH could begin with one dot, get the aoe dot at 30-ish, obtain the Thundercloud passive at 50, a third dot between 50 and 70, and then Biolysis and increased proc chances at level 72.
AST could have increased proc chance at every Malefic/Combust upgrade, thus using more and more cards as it levels up.

I'd immediately level every healer to 80 if we had such mechanics.

Oh, and before anybody tells me I'm just copying other classes, yes, yes I am. Because I'd much rather see healers get their own version of interesting dps mechanics than to get a simpler rotation than a lvl 2 BLM. The latter is what we currently have.