Making barriers taller is a terrible idea. The UCI-mininum height is already tall enough to make even carrying a bike over them fairly onerous for shorter riders. There's no need to make it worse. And USAC races have no minimum barrier height at all. This is good, because it allows for more creativity in course design, including lower barriers that are easier for riders of more varied skill levels to hop over. Adding a minimum height requirement, even higher than the current UCI height requirement, would hurt course design and make racing less fun for the non-elites, which translates directly to less participation and less money and eventually, fewer races. Having the option for more than two barriers in USAC races is, again, good, but as a minimum it would suck and would, like taller barriers, put more limits on course design and hurt the sport. No good.

The idea that crashes on downhills are "part of riding" is just baloney. Organizers do not have to include steep ride-downs in their course designs. Many of them, in fact, avoid putting the hardest or steepest possible features in their races specifically in the interest of safety. And riding down a steep descent is every bit as optional as hopping a barrier. It's a perfectly reasonable comparison to make. Racing bikes has some inherent risk involved. Hopping barriers doesn't factor very much into this risk.

My problem with you is that you think hopping should be banned because it's some overly-risky optional maneuver but you are flat-out wrong on the facts, there. The penalty for a failed hop is NOT that severe most of the time. Even before objections to your anti-hop stance on philosophical grounds, this is sufficient reason to say that hopping doesn't need to be made more difficult or banned. But you are digging in your heels and continuing to say that up is down and black is white. On top of that, your proposed "solutions" are really, really bad for course design reasons. So when I say you don't know jack squat about the sport, I'm not saying it to hurt your feelings or to be rude for the sake of being rude, I'm saying it because ignorance is the most parsimonious explanation for the poorly thought-through proposals you are making.

Here's a funny thing - there's actually a really simple way to take barrier hopping out of a race: don't include any artificial barriers on the course. While I wouldn't support a rule change banning artificial barriers altogether, I'm totally fine with 'cross races not having barriers. I don't they're an essential element of a good 'cross course, and some of best and hardest courses in the world don't have them. I'd be happy to do a race or two every year that didn't have any planks.