While it’s possible that this is the case, we don’t actually know that because the people with the right skills aren’t spending a lot of time and resources on experimenting with new ideas and concepts unless there’s profit to be made from it.

Chances of coming up with an idea for a new kind of OS that will bring great return on investment in terms of profit and market share are very low, so entrepreneurs are spending their time thinking about more lucrative ventures.

If we lived in a post-scarcity Communist society where everyone is free to do what they feel is important and fulfilling to them, we’d be more likely to see new and novel ways of interfacing with computers (and technology in general).

But we don’t.

Edit: Also, operating systems are a lot of work.