Who needs a razor thin iMac? It's a desktop computer, not a portable. And it's only that thin at the edges.
And worse, the smaller (21") model uses a laptop harddisk, and upgrades like a full solid-state drive costs hundreds of dollars more than the competition's, because the iMac is so compact that it has to use the super-compact SSD drive designed for the Macbook Pro Retina.
They don't often do it to a great extent, but this time (as with the former super-tiny iPod Nano), I think that this time Apple let their design aesthetic overrule function.
... My Mac Pro is running out of disk space, and it's also getting slower, something is wrong. I need a 3TB drive and a fast machine and lots of screen space. I'm in a confusion regarding all my options: install a bigger drive and make a fresh software install on that? Should that be Snow Leopard again, or Mountain Lion, which will force me to get new software I don't like? Should I get a big iMac? With a second screen? Or wait for the next Mac Pro, in the hope I'll like that? Oooooh, headache.