1) It dilutes the cards when you add a bunch of little boys and women.
2) There aren't enough fighters to make a division that means anything.
3) Women suck at fighting. All of them.
4) They are taking up roster spots/payroll that could be used on others.
5) Many viewers don't want to watch two people fight that they feel they could beat themselves (delusional or not).
6) I don't care who the best fighter who weighs 125 pounds any more than I care about the best basketball player under 5'6" or the smartest retarded person is.
7) Obviously the crowds don't like the flyweights. They booed the title fight FFS.
So you basically dislike them because they're small? Whatever sails your boat I guess.