"Culture" has this double definition of, on one side, "customs", and in the other as basically a synonym for "art". With extra points for "art" being this abstract thing nobody knows what exactly is, but everybody agrees that -whatever it is- it's "good".
So in Spain there is this national sport in which you take something, no matter how horrible, try to include it in the definition of "culture" and... since "culture is good" -> "thing is good".
Bulls? Yes, I hear you, you are making great logical arguments but... they are "culture" (purposely being ambiguous about whether you refer to "traditional Spanish custom" or "form of art"). And that's it, that's the end of the argument: Bulls == culture == good. Whatever you say, the answer will be "culture". And you are not going to argue culture is bad, are you?
And it's not only bulls. You can use it with whatever you want to support, and somehow in Spain it works quite well!