I don't really understand your meaning about whats your intension. I agree that eight belles death was tragic but not cruel, horse racing along with polo, show jumping, barrel racing, racking, are just as if not more demanding on the horse. Cutting a long story short, I wouldnt ride and expect to jump a horse that's too small and has never jumped....but I will ride and jump a horse big enough for me and fit enough for the job in which it is trained, and that wouldnt be cruel.
I don't think that many people intend to be cruel to a horse. A lot of people are just ignorant, have a lack of knowledge, there are things I did 20 years ago that were deemed fine...now I wouldnt dream of it because we have progressed in a way that we are more able to understand the natural horse and how to get the best from it. If someone intentionally is cruel to an animal...there are laws, and riding isnt something that is considered to do them any harm. Horse have been ridden for thousands of years, a cow has its purpose to us, a dog has its purpose and to us the horse is a riding and working animal but to ensure the horse is fit and fed properly and all the care is taken is our duty. Its only cruel if we make it cruel.