Here's my take on it:
Basically I think the problem is that unless you are a user who really
enjoys troubleshooting and always getting new things and learning them,
rolling releases aren't really that great.
With a timed or feature based release, you can decide when you want to
upgrade to the next thing and sit down and learn it, convert things,
With a rolling release you get new things as soon as maintainers feel
they are ready, so it's a constant flow, you can't really stop too long
and put off learning or troubleshooting.