In MMA, just like in all of sports, everybody loves a champion. We like seeing the champion defend their title and we like seeing a new champion win the title away from the former champ. After all the training sessions and media obligations get finished, it all comes down to the fight itself.
Once the fight ends and the confetti is swept away from the cage, all that remains is the belt that the fighter has earned, symbolic of their effort on the evening. No matter how long the fighter holds the championship, he or she only holds the championship for a moment in time.