An excellent point; for example, although I don't have any reason to think RMS himself did this, Emacs 24.4 will have file change notification support across all platforms where it compiles and where such notifications are available.
I grant that's a somewhat overdue feature for Emacs to have (e.g., I've wanted it ever since I set up Dropbox to synchronize my org-mode files across all my boxes), but it's definitely evidence that Emacs isn't lacking of maintenance and improvement.
I wonder: If Emacs rarely gains new features in core, is it because there aren't enough developers doing enough to improve it, or rather because people are having a hard time thinking up new features to add which Emacs doesn't already have?