Well, that's the difference between actually not caring, and just wanting everyone to know you're not caring. I'm not caring, guys, look! LOOK AT ALL THE CARING I'M NOT DOING HERE!
SteamVR isn't an API, though. Developers don't want to have to make two different versions of their game for competing VR standards. We don't want another Direct3D/OpenGL 'competition'
Also bear in mind that some publishers aren't big fans of Steam (hi, EA!) and it all starts getting complicated.
I'd be more interested in a standard VR API than another headset. The last thing VR needs is a pissing contest between rival manufacturers, each with their own way of implementing things.