I keep seeing threads from DPS who want to "fix the lack of tanks in LFR". I thought it'd be more useful to see why people don't tank LFR at the moment. Poll inc ...
For myself, I currently tank LFR on my monk but will stop soon since he doesn't need the gear. He's also the guild's MT and we're running Flex.
I've tanked a couple of times on my DK but often don't have the free time to do another set of LFR raids.
I would tank on my warr occasionally but he's still carrying a blue shield (not had one drop in any raid, and he's done MSV, HoF, ToES, ToT). I already know the abuse he'd get in LFR with a blue shield.
I might start tanking on the druid again, but I've not really played him this expansion. At the moment he's in mostly Timeless pieces, but should be fine once I've done a heroic dungeon to see how the bear's changed.
 Aaaaand I forgot the obvious poll option - I *do* tank LFR. Ah well, put that as "other"