You can have your 32 bit 3D rendered icons, but I bet when you have a hard drive full of different ones, it all looks like scrambled eggs, and you then have to ignore the icon coz you don't know what the hell it supposed to represent, and look at the name underneath it, with the icon becoming nothing more than the place you click, defeating the whole purpose of having a GUI.
That really depends on the icon theme, to be honest. I try not to have different icon themes concurrently. The stock 4.1 update 1 icons are nice, if a little big.
Over the years, I've lost interest in GUI eye candy, and just want speed and functionality: hence I'm installing the stock 3.1, 4 colour GUI, which is a speed demon, and just does the job.
I can certainly understand that sentiment. However, if you are an RTG user, there is absolutely no benefit whatsoever in using less than 256 colours for your screens, even if you only use 4 pens.
