What about Linux kernel or SQLite maintainers? Aren't those great programmers? Also if the software "they" created is so great, why wouldn't they want to maintain and extend it?
As far as I know, programmers love maintaining great software, but maintenance doesn't mean "bloat it with unnecessary features" or similar. Optimizing performance, make it more reliable, improve the tooling, cutting out the fat and similar are things that are challenging and engaging.
I think programmers want freedom, agency and ownership of something great. Yes, part of that has to be tinkering and writing new prototypes of things that might or might not go somewhere, but it can't be all of it for everyone right?