OS-X doesn't have better aesthetics than windows?
He's talking about the machine. He's saying the aesthetics of the machine should not be more important than what is in it, i.e. like a polished turd. The current iMacs make many concessions to get into the form factor they are currently in, and talk of them going thinner just means they will most likely have to make more.
If the machine were an inch deeper, but could house a desktop GPU, and user serviceable hard drives...would that not be great? Would you even NOTICE the physical change? Certaily not in use.
Extreme thinness on an iMac for the sake of thinness is ridiculous. Does anyone here remember the first iMac?