Yeah, they are morally dubious at best. But there's just something about watching things fight to the death that makes it so fascinating. Though I agree that it is best if they are each in their own natural environments rather than just shoved in a glass box together. They should have the option to disengage, too, because it's also interesting to know when two killing machines opt to not try each other (and based on the one video I did see of wolf spider vs black widow, I'd guess most of them would go that way because the wolf spider wasn't very interested in getting anywhere close to the widow and only killed it in the end because it kept trying to web it up).

That makes me wonder how many of the animal vs gladiator fights would have resulted in them walking away from each other.