UFC does best when there are long reigning champs because that makes for story lines, the proverbial 'good vs. bad'.
People want to see a dominant champion, and everybody else wants to see that guy get beaten.
Parity works for team sports, and even then there still needs to be a little continuity (like Patriots, Yankees).
I hope UFC does something about this, aside from the most die hard fans nobody wants to see a bunch of new guys every few months, especially because the future of the sport is basically gonna be a bunch of guys with the same styles and skill sets.
If anything I can definitely see UFC losing a lot of interest down the road because of this.