IN MY OPINION!!!
I don't know anything about jumping. Never done it, and never plan to. Im not saying its cruel, its just I don't know anything about so I don't necessarily have an opinion on it. If the horse looks like he's enjoying it, then I don't see it cruel.
Im not going to get started on harsh bits and stuff like that because ANY bit is harsh in a horses mouth. No bit is harsh, its the HANDS that are doing the damage. Even the harshest bit can do wonders for a horse, as long as the rider keeps in mind how much powe he has in the bit.
I don't think bareback riding is hard for the horses back, so to all the whiners on here saying its bad, get over it! The indians didn't have saddles!
As far as the other gimmicks go (martingales, tie downs, draw reins, side-pulls, hackamores, crops, spurs, etc.):
I use a running martingale because it steadies my hands. My horse is very bouncy, and he always will be. He has a very low headset naturally. My hands do bounce, but not very badly. The martingale steadies the reins so they don't bounce and put pressure on his mouth.
I've seen draw reins used at many horse shows. The trainers get on and crank the horses head down in the warm up ring. But when it comes time to enter the arena, off come the draw reins. And what happens? The horses head goes up! Big shocker! Its only a temporary fix. I've only seen them used that way, and im sure there are people out there who use them properly, but all I can go by is what I've seen.
Only two of the lesson horses use hackamores at my barn. One has a hebranoma in the side of his mouth, so he can't have a bit, but he is guided mostly by leg pressure. The other horse has always been in a hackamore because he doesn't need anything else. He goes easily with a hackamore.
I use spurs on some horses, but that doesn't mean im constantly poking them in the side. Some horses need a bit more encouragement than others. I have never caused sores, bleeding, or anything else with them. But I will admit I have seen spurs used incorrectly. One of the biggest: the spur stop. Horses naturally move away from pressure. When you push a horse forward with your legs, their first instinct is to move away from it, not the other way around.
Hope I helped :)