[kiwi_jono]

I can't imagine K mount being so expensive. You can buy plenty of new super-cheap k-mount lenses. Some completely manual (Mitakon) slightly less manual (Zenit, Horus Bennu), auto-aperture but no AF (Samyang), plastic K-mount (some Pentax DA lenses). And you can get top of the line metal, WR, AF and auto-aperture K mount, as well. Its been used for full frame lenses, fast lenses (f1.2),.. very few limitations, really.
The only problem with K mount is that Pentax doesn't support third party lenses perfectly (regarding focal length and lens ID).. well, and maybe that there aren't as many Pentax cameras on the market to give a significant profit to a third party lens maker..

I agree.
Although I don't see it as a bit issue, I also think modernising of the mount could be achieved while keeping backwards compatibility (even if there were some restrictions).
I do think a key advantages Pentax has is their backward lens compatibility (its one of the things that sold me on the brand anyway). Even an adapter would be better than no compatibility. I have never forgiven Canon for obsoleting FD mount - without even an adapter being available.