Well, if you're looking at it from a 'can they provide the healer mana without losing DPS', then the ranged 'can't afford it' either. You lose DPS promoting your turret, just as a SMN will lose ruin 3s if they donate mp to a healer - it's an emergency skill you use as a last resort to salvage an already bad situation.

But that's an interesting point I guess, if they're diluting tp/mp support into cross-role skills like that it does seem like a good sign for the ranged.