I generally use BM all the time, as I am so used to it I actually do more dps than higher specs (nowdays that is very hard to do with teh internal balance issues).
In Wrath:
Mr. Average Him - You are BM? GTFO.... I'm gonna ruin you with Surv...
Me - OK give me chance
Mr. Average Him - Jesus......how......my life is overrrrrrrrrrrr.
(Of course if there was a similarly skilled Surv, then I got owned. But not by much.
The suprise from other hunters is why I stuck with BM
----------
Incidentally BM is very useful in some kiting. The basic skills you are given as a hunter allow you to kite mobs effectively anyway, so leaving a static 50% of your damage DOt on the boss is cool.
Last boss BRC is a good example. No point damaging the adds, yet you need to attack them fairly often to keep them on you (in the average group). Your pet stays on boss. Win.
Have our pug tank whipe three times on trash in the Stonecore. Whip out crab tank, tank through a few adds waiting on guild tank to come join us. Guild healer is lulzing about how it's easier to heal my pet than the baddie tank.
For OP soloing with Spirit Beasts, that's the only reason I have a BM spec. I don't enjoy BM all that much, really. Survival in Cataclysm is one of the most enjoyable DPS specs I've ever played.