Mind manipulation is a very powerful thing,not questioning that at all,BUT,there's also the downfall of it in the fact that there's gonna allways be people out there that have indomitable minds or can just flat out resist it through sheer force of will.
whereas if i summon 18 to the field and do something lewd with her,something they wouldnt expect at all,causing them to question just what the eff is going on and completely take their mind off of the fight,well,that's a tactic worth using imo.
of course,there's pros and cons to most everything,and ultimately this is a lewd game,so i'm not about to get into that,but personally,i'm all about taking out my foes by doing lewd summoning stuff.