I believe that when a fighter wins a world tittle, he should welcome all challengers. I just hate when I hear about a guy with a title and his team says he’s not ready to fight anybody, why push him towards a tittle then have him look like a coward by avoiding somebody
There are certainly a lot of factors that go into how fights get made - I'm going to think about just two.
First, I assume there is a degree of feeling like the fighter has earned a rest. It is a long hard climb to the top, so I can empathize with the urge to stop and catch your breath. Enjoy that belt, and that payday.
Second, from the contender's point of view. If you've been watching and waiting for Champ A, and then he loses and Champ B has the belt, maybe you have to re-adjust your own schedule. There can be a lot of planning around who you're going to fight - not only the business, but the fighting end, too. Is the new champ similar or different to the previous? Imagine preparing mentally for an orthodox boxer, then a southpaw brawler wins the belt - that makes for a very different fight!
All in all, of course I want to see the good fights get made, and made at the right time for both fighters. So much involved in getting that to happen.