Plasticity got an amazing deal on the Parasolid kernel (probably because Siemens are curious about the concept artist market), so that’s why it got all those nice features.
The guy who apparently played a major part developing the Rhino kernel left to do Moi, and even he decided that he wasn’t going to do that again and licensed kernels just like the Plasticity guy did.
Rhino is one of the few unique kernels still out there… but again I have to wonder if anyone who still works at Rhino knows the ins and outs of it, or how to properly develop it. Yes, it’s very difficult and it takes a long time, but looking at the close to zero development in critical areas in Rhino for the few years I’ve used it… I still don’t think they have in-house know-how honestly.
Now, Xnurbs was mentioned, and it’s crazy to me that McNeel haven’t hired them yet (former PTC people apparently) and now there’s Cyberstrak (weird name but apparently former VSR people) which also should just be a straight up hire.
A McNeel employee recently said on this forum that Industrial Designers still are the single largest customer group, but I don’t think it reflects in the development of Rhino (I bought V8 to get some bugfixes, thought right now there’s more new bugs than fixes… but there’s nothing new in there for me otherwise and even the same old UX issues which daily wastes unnecessary time that doesn’t even have to do with the kernel… it just has to do with not listening to that “largest” group).