I've been thinking that the K-mount's longer flange distance doesn't make a huge difference on lens designs, except for the smallest types.
The attached diagram shows 5 different designs. A traditional SLR/DLSR can only support "Long" and "Telephoto A". In contrast, an average MILC can support all of these lens types.
I think that the K-01 can support 4 of these 5, which covers a lot of ground. The only type not covered would be "Short". Which eliminates the possibility of pancakes falling somewhere between 16-30mm. But other than that, I don't think many lenses fall into "Short".
My post isn't a dissertation on the topic. Some problems need addressing. First, in some cases focus motors would have to fit or drive recessed optics. Second, the mirror box is rectangular, which doesn't lend itself to housing recessed optics without accounting for the rotational bayonet attachment.
What I'm trying to say is that certain lenses can house elements inside the mirror box to open up possibilities.
And on a somewhat unrelated note, I think that fast telephoto design always looks like "Telephoto A" or "Telephoto B", which is probably why neither µ4/3 nor E-Mount have fast telephoto zooms: they would look embarrassingly large, just like a DA 50-135mm stuck on the end of a NEX body. In this case, the K-01 looks better, too, because it has a reasonably large body to attach reasonably large lenses.
PS I'm just throwing ideas around, if some optics professor wants to school me then please do. I'm not saying that other systems are advantageous or crippled. I'm just thinking aloud.