Building IP-free core/wireless/... seems to be orthogonal to their goal. I think they would prefer to use such components, but I don't think they are in the right position to build them. It's enough of a problem that cores with NDA-free docs are not common (Bunnie wrote about it in the article).
Then there's the wireless stack and peripheral space which is even more complicated.
Edit: this was my intention when I went to university in the early 90's but I found sitting in front of a Sun workstation drawing squares (gates) very tedious.