At that point you run the risk of getting punched in the face by SR touch spells.
And you wouldn't run that risk that much anyway.
D&D has no official called shot system that I know of since it is assumed you're
always trying to make the best hit possible, but the armors are illustrated as having helmets and such even though there's never talk of needing helmets (because there are no "headshots").
So "punched in the face" sounds really effective until your bare knuckles meet steel visor, or worse, armor spikes.
Fist of StoneWhat? Did you hear something?
Basically the game suggests "describe your action
after you resolve it."
So you CAN be like the dozens of roleplayers I've suffered who talk about how they're going to do flip over and kick this guy right before they stab that guy "IN THE FACE" (Always in the face or in the nuts), and then they roll a 2 with their attack bonus of 2 and just wasted everyone's time.
Or you can successfully make your melee touch attack and successfully overcome their SR, at which point the GM says "Wow, you must've punched him in the face." After the two 2s the GM just says "Miss" and you've thankfully wasted no more time than you had to describing your kung-fu sorceror.
It's lame watching casters try to act like monks, anyway. It shows that what they
really wanted to play was a monk,
and that they aren't playing their caster right (Nothing shows that the monk can be played like a monk).