That's a feature, not a defect.
If you want a distro that develops, there's always Ubuntu or Fedora.
My point wasn't that Debian is being developed too slow. QA has never been fast.
My point is that Debian nearly always distances itself from the development and the developer community.
In other comment I also mentioned the APT. If Debian was today debating a packaging system, they would never ever opt to *develop* the APT like they did in the past, but they would take the RPM and try to live with it.
Otherwise, just look at two good examples of distros evolving: SUSE Studio and Ubuntu Launchpad. Lots of things which happen there rarely see the daylight - but they allow distro to play proactive role in bringing together the developers and users. (But of course, SUSE Studio and Launchpad are targeted at two different kinds of "developers" - first is for developers of distros and second is for the developers of the software.) That might seem superficial, but it allows distro to actually learn about the new trends and things people are doing with the software. They need much less guessing what/how to do in the next release. OTOH Debian, beside the heavily unreliable popcon, is very very much closed and unto itself.
That distance also plays role in how Debian's decisions are made. You can't roll-out something new and experimental in Debian and expect later it being adopted in Debian main. No. Because Debian wants to have a project with proven track record. And you can't get the "proven track record" *in* Debian - because the project will not be accepted without "proven track record". That is why the development happens in the Fedora, Ubuntu and SUSE. Rarely in Debian.
And why is this on-topic? Because Debian with migration to systemd would in some aspects become Red Hat, which is not something I'm particularly happy about. Because, though RH doesn't develop much of the systemd itself, it does quite a lot of work on systemd integration. Because they played role in its development. They gave the project fighting chance. And all it took for them was to say the developers: OK. At the same time, if you check history of attempts to bring upstart into Debian (which is much longer than the vs systemd discussion), Debian wasted literally years discussing, and mostly dismissing upstart because it was used by only one distribution, despite Canonical's pledge. Result? Red Hat has nurtured the systemd - and Debian has strangled the upstart.