It's a difference of culture.
>>329759made the exaggerated claim that even rapists wouldn't stand for it, but the fact is that it's popular in places like Spain, so no matter what you say it's at least more socially acceptable there than it is here (here being the US, I suppose).
There's something about the clean image of bull fighting that's alluring though. It's a big, frightening bull being tricked and bested by a single man with a cape. People enjoy watching it.
If it was more obvious that the bull was being tortured and crippled in order to make it safe, you might draw a smaller crowd.