I personally got a lot of mileage from Rich's idea of simplicity and decomplecting, especially at small scale. It is nice to have everything decomplected. You can just drop what you don't need anymore, compose, add new things... while avoiding breakage. Many other authors advocate the idea of not overloading concepts in design. That said, we need to be careful, especially at scale. Something that may seem simple can become a mess. I would say that something like software semaphors are simple in Rich's sense. I don't think they're simple at scale. Alan Kay has a also a talk on simplicity where he emphasizes the importance to find "slightly more sophisticated building blocks". () But they both seem to agree that "easy" shouldn't be a goal.

Yes, I think the 'slightly more sophisticated building block' is a very keen insight. Often with simple things, not all problems are solved and then we add layers upon layers to implemented the missing things.