Fun?! There's no place for fun! This is a game dammit! Games are for winning!
Seriously though, that's a big part of why I have been Blood this long. When they fixed some pretty big holes in tanking as Blood for 3.1 I decided to give it a go. It really just appeals to my personal tastes.
Before they added ToT and flipped the talents around, Frost tanking always felt a little blah because I felt like I needed to lose certain play style elements, or not use them well in a tank spec. I loved dpsing as dual wield frost (even before the talents actually supported it). Now it feels pretty great, to Blizz's credit.