I find it odd that people use their pinky to type parens. When my fingers are on the home row, '(' is above my middle finger, and ')' is above my ring finger. Typing them with my pinky would require me to contort my hand.
If your fingers are on the standard home keys (index fingers on "F" and "J"), '(' is between the middle and ring finger and on the normal (inward) path of the ring finger as it extends, ')' is between the ring finger and pinky and on the normal path of the pinky as it extends.
OTOH, if you keep your right index finger on the "K", which is less standard, then those become naturally on the middle and ring (and it may make sense for programming, but less for general typing -- the standard home position is based on where the letter keys are, but the extra symbols on the right are more used in programming than general typing, so moving the right hand one key out makes some sense.)
Many people seem to type it the way you have just suggested (middle/ring) - myself included. I'm currently re-training myself to do that properly.. it feels weird at first, but I'm starting to get the feeling it will actually be faster.
Your touch typing can always be better, right?