If you think HotW's active effect is useless you're woefully ignorant. And then I checked OPs gear/raid history...
HotW is amazing. And far more than a 'situational' bonus; It is very meaningful dps, either added up over an entire encounter or for help on a specific burn phase for adds or otherwise.
The tanking aspect of it can be somewhat questionable in a raid environment, but then again if you need it to tank, you lost a tank w/no brez and you probably deserve to wipe.
The healing it can do is, just like the dps portion for a healer, is meaningful.
Also, for a resto druid, the thing's like a mana cd. If you reach any part of a fight where your other healer can pickup more slack, or you're free to dps hard w/HotW, that's 0 mana spent for x seconds you dps. That's big time mana back broski.