This level of "giving back" is not trivial: I have often benefitted from seeing the source code of other projects and deciding I don't want to use the library, or seeing the code and deciding to modify it or take a different approach - or seeing the library and realizing that I wanted to try something similar, but this library shows me why I shouldn't do it. Maybe others will similarly benefit from seeing my stuff. If they see my stuff and think it's deficient, wonderful! Alter it to make it fit your needs, or use it as an inspiration for your own fresh rewrite.
But I'm not maintaining software for other people. God bless people who do; that's wonderful. But it's perfectly OK to just post stuff up in case someone else wants to use it. When people see the code on Github they think "oh I can make feature requests" or "I can send a PR." Fair enough - Github is "social coding" after all. So I just won't put code on Github.