If they offered an iMac with a touchscreen at a remotely reasonable price, I would buy one the day it came out. And I don't EVER buy computer equipment, iPhones, or anything when it comes out.
The amount of productivity I would gain and options that would open up would be astounding. Mice, trackpads, even the magic trackpad, are not a replacement for a touchscreen.
I work in entertainment lighting. Pretty much every major console these days is built around a touch interface. I've been using them for years and years. Both on the consoles themselves and using PC all-in-one systems. My arm never wore out from using a touchscreen too much. I never got extremely annoyed by fingerprints. I'm looking to build my own system right now, and want an iMac to be at the heart of it so that I can have two external monitors (which no PC all-in-one has to my knowledge), and so that I can boot in either PC or Mac. But, without buying expensive external hardware, that option is pretty much dead. So, it looks like I will have to use a PC and settle for one external.
It honestly baffles me how many people are fighting against a touchscreen iMac. it often seems like they think that if you have a touchscreen, then you can't have a keyboard or a mouse, which is simply ludicrous. But, it often comes back to "if Apple says no, then that must be the way!"