I think so yes. I do horseback riding for about 12 years now and as I know, some horses really like it and really want to work for a person (at least that's how I experience it. We will never know). People always think the best for an animal is to let them go in nature, but we humans can't never guess what an animal actually thinks and feels. Maybe he does like to slender it's whole life in nature, maybe not, but taking away a pleasurable sport from a lot of people because of one doubt that it might not be pleasurable for the animal is ridiculous I think. Same goes for zoo's and stuff.
I knew a guy when I was little that did birthday parties for kids and he had a well trained dog who was mostly there for the kids to play with. I'm fine with that but I'm worried about more professional places since it's known now that Circuses beat the shit out of their animals to obey which isn't cool.