Besides, you can build an AR in a variety of calibers other than .223. There's the various 6.Xmm cartridges, the 460SOCOM, the 50Beowulf, the 7.62x39, etc.
As for hunting with an AR, I'm not particularly driven to do it. I'm more of a traditionalist in that regard and prefer something with blued metal and wood. I don't care if anyone else does it, it's just not for me. Hunting is a good excuse to buy pretty rifles like my Winny Featherweight or a Mannlicher-Shoenauer carbine.
Chris