Maybe my view is tainted by how Next.js implements/propagates it, but the last ~5 years of React has mostly seen iteration in the form of RSC (React Server Components), which in many projects manifests in chaos and creates a steeper learning curve.

I do think that React in its history has been able to evolve quite meaningfully, and in a good way (lifecycle methods -> hooks), but in the more recent years, less so.

> How much innovation is needed

Enough to make it worth it to switch, but not so much that it's hard to switch

> often iteration is better and cheaper

Fortunately React has had major changes over its lifetime that iterating with React was/is the better and cheaper solution.