You do get to use Ruin 3 instead of Gemshine sometimes - especially if you're Savage raiding, and you need to place Ruin 3 at certain point in the rotation (not at start before because of buffs, not at end because of movement).

But I agree with the button bloat. Having a button for ST and another button for AoE does not make the job more difficult - it's so easy it's stupid. I'd rather some buttons are simplified and leave space for more buttons that add complexity - like having more summons that are used in different ways, or giving more freedom over when to summon Bahamut and Phoenix. I feel like SMN was especially made as a class with few buttons and very compatible with controllers.

Main issue I see with SMN in Savage is how inflexible its burst window is, and no way to correct one after it has happened. I know it's about not having to think and just executing summons, but having some freedom to move the big summons and small summons around could give way for some cool rotations.