> I don’t want a custom look and feel for each app
I'd agree personally, but when you look at the huge success of things like WinAmp's themes back in the day, there clearly is (was?) a large market for it.
You have the situation confused. The market is for users to customize applications in the way that suits them.
The problem we face right now is that this has been flipped and applications are now forcing developer customizations onto users and removing any and all choice or customization. Up to and including ignoring and overriding OS level customization.
People talk about functionality and features (well, tech people do), but for a large part of the population, the eye demands its share. Your application doesn't look good? Sorry, skipped it already. First use doesn't feel intuitive? Delete. Another app does the same, perhaps even worse, but has funkier colors? Switch.
If a framework cannot provide you with the right looks, you have to to override it. Hence the mess.
I'd agree personally, but when you look at the huge success of things like WinAmp's themes back in the day, there clearly is (was?) a large market for it.