For every cluster deployed, there must be hundreds or thousands of single hosts deployed to serve up wordpress or static content. Simple stuff written by a weekender, maybe with slashdot effects handled by CloudFlare. I think these guys would find systemd's respawning awesome. Much nicer than configuring and tracking down memory leaks in God, that's for sure! http://godrb.com/
Yes, clusters need more development effort and more powerful tools, but don't let that get in the way of the 80% solution.