Plenty of guys would want the job. Kelvin and Lon (and even to a lesser extent Capel, who I can't stand as a coach) all showed you can not only win big at OU, but you can turn things around quickly. We missed the tourney 3 of Billy's last 4 years, but Kelvin got us in the dance right away. Capel inherited a tough situation because we lost players and recruits when Kelvin left, but (thanks largely to Blake), we were in the tourney in year two. Lon inherited the biggest mess of all, and we were in the tourney (and ranked) by the end of year two. Moser walked into arguably an easier situation than all of them. He has failed, but that doesn't mean a coach couldn't come in and turn things around quickly.
The other thing to remember is that it's not like OU is alone in having to fill holes. For every team with several guys who have played together in a program for three or more years, there are several that turn over a big chunk of the roster each season.
We have slipped, no doubt, but we are still a desirable job for a lot of coaches.