I guess I still wasn't clear. Many of the projects I've worked on have been in relatively active development for 10-15 years. Even with new features being added daily, (not just minimal maintenance) a code-base like this needs more care and feeding in much of the work.

New features in these cases require more knowledge of current libraries and code and less knowledge of the language and new techniques. Some decade-old design decisions may limit the directions you are allowed to go. I've seen many fellow programmers forget that these decisions are an artifact of the current system and not an absolute of programming. Over time, this can erode your ability to do basic programming unless you work to practice the basics.

When I can, I truly enjoy working on new projects where I can use the latest best practices and the newest libraries. However, much of the work I'm paid to do has limitations that prevent that.