I've decided to get the Choice package (opposed to Entertainment) just because they listed 3net and n3d. I got disappointed to find out that, despite advertising n3d, directv didn't actually offer it. So I was willing to pay a bit extra just for 3D content. And if I decide to get a pay per view movie, I'll probably get the 3d version.
There is some 3d content out there (movies, nature documentaries, etc). I think active 3d is inconvenient as long as you need to make sure that the glasses are charged. But passive 3d is pretty convenient for me - I don't get dizzy by watching more than 2 hours 3d content and the polarized glasses don't require batteries or any charge.
3d had a chicken and egg problem - it was over-advertised but it didn't take out because there was not enough content (and also, due to the fact that active glasses are not very convenient).
While BBC, ESPN and n3d were dropped in 2012-2013, Netflix decided to add 3d content in 2013. Directv (like Netflix or Comcast) can probably measure how much interest is still there for their own 3d channels and provide that info to the studios and broadcasters...