I'll reiterate what I said recently when confronted with a pair of argumentative guys in my FLGS whining about the dangers inherent in maximized touch of idiocy attacks: Any high-level wizard who gets close enough to his enemy to use one of these spells is already adopting a losing strategy. (Of course, in the case of ToI, there's always the option of picking up arcane reach and staying far away, but...)
It is true that a Ftr1/Wiz5/EdK9 who takes this feat can, once per day, whack his target with a maximized vampiric touch spell for an automatic 156 hp damage. It is also true that the eldritch knight's single-classed wizard counterpart can instead blast his target from a nice safe distance using empowered disintegrate, and suffers no risk of AoO, or any return melee attack for that matter. It is also true that the eldritch knight had to use three feats, two of which simply aren't that great (Weapon Focus [touch] and Imp Critical [touch]) to achieve this combo, and can only do it once per day.