Never really bothered me that much. I mean ideally it wouldn't happen but that type of ship has long sailed and I don't see the value in fooling myself about it. Our culture is built around the casual exploitation of, and disregard for, animal lives. If you've ever gone out for chicken wings or done any number of other things you're complicit in the unnecessary death and torture of animals - but you've outsourced the brutality so you don't have to look at it. Heck, a supermarket meat section is a veritable monument to brutal slaughter and creatures raised to give their lives for the material pleasure of a consumer base. At some point I figure why not just admit what you're doing and what you're part of - and say "Sure, I'd like to see some dude fight a bull."
I can't help but feel like this outrage is a bit of a hypocritical indulgence enjoyed by people whose lifestyle is a gold stamp of approval on a series of practices which has lead to exponentially more death and suffering for animals than bullfighting ever will - but because they don't ever have to see it, and rather just create massive demand for it, they can take a sober step back, put on their serious moral face, and start signaling their virtue.
There are a host of things most of our lifestyles endorse which are every bit as bad and, conceptually, arguably even worse than this, with generations of animals raised as virtual slaves to - literally - satisfy our appetites with their deaths. I have trouble taking myself seriously if I pretend like a bull fight is some unforgivable outrage that I just can't stand.