You could also argue that this fragmentation has been a strength that allowed innovation and competition. Debian has a great package database, but now rpm-based systems have nice package database too. Ubuntu innovated with upstart, and now we have systemd. Both are a way to codify and improve the traditional script-based startup infrastructure of Linux systems into faster more declarative systems (I for one like not having to wonder about repetitive shell script files).
All of these have neat ideas in them; for instance yum on Fedora has an extension that allows one to download diffs instead of full binaries, something I didn't see in Ubuntu.
So I figure this fragmentation is both a strength and a weakness. I do think that it's worrisome that Ubuntu seems to be pulling away from the rest, but perhaps that's mostly perception and not technical reality; Fedora has introduce lots of new stuff too, for instance. I hope and expect that in a few years we'll see some more coming together of solutions again. Let's hope pride and stubbornness and NIH doesn't get in the way then; people do tend to dig themselves into defensive positions.