Ahh, bullfighting thread. Always funny to see a bunch of people discussing on something they have not a clue about.
Common and mostly valid arguments in these cases (some already exposed here) are:
Pros:
1) The fighting bull is a special race of bulls born to die in the ring dangerous and without any other use. Without bullfinghting there is not fighting bull, or populations would become really scarce to say the least.
2) Fighting bulls are cattle but also are wild animals and needs lots of wild terrain to roam freely along his life with almost not human contact. Which means an important plus for natural ecosystems in Spain and other bull countries, with many species depending on these woods called "dehesas" in Spain (i can say it myself since i live in a fighting bulls zone).
3) Not only fighting bull´s life is better than common cattle life, but also fighting bull death´s is better than common cattle death. Bull has a remote possibility of surviving too and a not so remote possibillity of goring his killer. In fact, there is a real fight in the ring until the end of the bull. It is only that the bullfighter is so well prepared (normally since being a child) that it seems a dance, but anybody not properly trained would be gored in seconds.
4) The aesthetic and cultural thingy.
Cons:
1) Near half a hour of pain, blood, fighting and death. Something the bull surely doesnt like.
2) Bull has a very slim chance of "winning" (winning here means to be indulted. Goring the bullfighter does not mean that the bull survives since it will be killed by the next bullfighter).
3) All is done publicly, so some people gets scandalized.
4) Last and worst: The bullfighter outfit seem gay.
This said i dont find bulfighting specially interesting and would not pay (again) to see a bullfighting. I wouldnt care if someday bullfighting become something of the past. But it must be a natural proccess, not accomplished through forbidding laws to please the prejudices of some prudish people.