It’s more reaching the optimal solution rather than lack of innovation. Look at commercial airliners for example. All of them look very similar, except for the number of engines, and size. It’s not the lack of innovation, it’s due to the fact that we have reached the optimal equilibrium of what an airliner should look like, given the restrictions and design goals of what an airliner needs to be.

The same applies to other day to day products as well.

But innovation still happens, by creating a new class of product. All carriages started looking the same, until the automobile was invented.