tanders
To the best of my knowledge, GroobyVR is still with us. In fact they just recently uploaded a scene. As for 2D videos, well, it's a matter of taste I suppose. Additionally, there are a handful of users that suffer headaches from artificial depth in 3D VR, and the 2D can help alleviate that. It also can boost performance on lower end headsets and result in higher framerates and better video quality for those with struggling hardware.
Obviously, most of our users are here for the highly immersive, high quality, HD VR videos with full 3D to really bring the scenes to life, but if there are a handful of studios catering to a 2D audience then I don't personally see the harm in that. We do try to tag flat videos properly so you know what you're getting in advance.