I suppose if you asked a shrink they might say I enjoy being a tank because it gives me a sense of power and control I dont get anywhere else. And they'd be right
Always played a hunter (in fact i have one of every class at 90) but switched to my warrior for my guild due to always having tank issues on our roster. While I occasionally miss my hunter, and I actually still keep him geared up as best I can, as long as I still play wow, i'm going to tank for my guild.
Also, as others have said, having high health and being able to just waltz right into a pack of 10 mobs and laugh it off is awesome.