If you use clw in this manner, then you should also be making attack rolls on your allies every time you use it on them. After all, you might score a critical hit and get double healing.

Come to think of it, why stop there. Bull's Strength, Endurance, and the other buff spells are touch as well, and if you wanted to put them on a hostile target, you could make a touch attack. Do you get critical Bull's Strength's as well? Or a coup des Cat's Grace?
'okay guys, here's the plan. Lidda, we're going to tie you up so that you are helpless. Then, Jozan will coup des gras you with a couple cure spells to fully heal you and then a Endurance. We'll untie you, put Mialee in the hot seat, and go at it again.'
In a related note, if you cast a cure light wounds spell on a hostile (non-undead) opponent, would they get an attack of opportunity against you? I'd say yes, since there's no consequence to ignoring the attack (ie, it doesn't hurt you.)
Seems to me to fall in the area of too much extrapolation on the rules.