I tank. Not to the public, but I tank. I barely do dungeons (hc, mythic or mythic+ either one) as it is, lack of time and desire to deal with randoms. But for the guild I tank both raids and dungeons if/when wanted, on several chars. Got less time than ever (ironically in one of the more timeconsuming expansions) so don't get to do it a whole lot anymore though.
As far as why not to the public (which was the real question OP meant to ask, I guess), I already alluded to it; while most people are fine and dandy, even the reasonable sort want to decide how we roll and I'm too lazy to deal with it; so I don't. Less tanks for the queue but ah well.