I want more ground-targeting.

[Archwizard]

So, if you mean more persistent environmental effects, then as long as they either A) automatically center under your target as Slipstream does or B) automatically center under you as Doton does, the only major objection I can see is "what if the tank moves the boss." Otherwise though it shouldn't be much of an issue; just center under an enemy target for caster/ranged/healer offensive skills, under yourself as a melee/tank, or under an ally for healing/defensive/supportive skills. (Maybe even play around with things like casting a persisting AoE effect that follows a pet, or your target, like putting Spikes on a tank or making explosive DoTs.)

Honestly, I macro abilities like Salted Earth or Earthly Star to behave like that anyway, and even did so with Freeze last expansion just for the tedium (although there's sadly no conditional for "target IF FRIENDLY" for effects like Asylum or Sacred Soil, so I do drop them in weird places under bosses on occasion). The time saved from not having to manually target makes up for the time lost to the macro itself.

If you mean more effects where you actually have to target the ground though? That would be hell on controller players. Even as a mouse and keyboard player, I find the frequent inconvenience of manual targeting outweighs the rare "convenience" of precasting on a spot.