If you don't yet know whom you want to hire then yeah it's probably a good idea to interview a diverse group of people. The thing is occasionally a great coach becomes available and you know you really want him and there isn't any need to interview lots of candidates. For example when the Buccaneers fired Tony Dungy the Colts hired him just a couple of days later without seriously considering anyone else.

I hate the idea of forcing teams to pretend like they're considering a candidate when they actually aren't. It's a joke that's masquerading as progress when everyone's really just bullshitting each other. This happens all the time, as Lukie mentioned and it's the worst kind of tokenism.