1) In the past, all divisions have enough fighters or challengers. Now what we have, fighters fight against each other for 3-4 times
It's a show business after all, if another re-match is something that the fans prefer to see over any other match-up, then a re-match it will be. Personally, I don't see it as much of a problem and I don't recall a situation when it would bother me really. We usually see it when the previous fights were close and exciting or when the number 1 contender is dominant over others and deserves another title shot.
This generates more money to the UFC, a money that could potentially solved this issue:
3) A lot of fighters wish to move or try boxing. Mostly because of high payment there and low payment in UFC.
This was a real problem in the past and I'm not sure on how much has the situation improved. But we shouldn't have a situation where fighters from the top 15 of the biggest MMA organisation in the world are struggling to pay their basic bills.