Yeah, they do take a fairly lengthy time between releasing games. I was surprised to see how little titles they've put out since Penumbra, I thought I had maybe missed a few between Amnesia and SOMA. At least the end products they put out are generally worth the wait, however.
Also, that is a huge bummer that SOMA can't be played in VR. It would be an amazing game to play in that format, and I'm gonna cross my fingers with you that they port it to the next gen of it. By the time I get my VR headset in a few years, I wanna be able to play it, damn it!