Walls are situational. Youre also not boxed as often in if youre fighting outside. Regardless in comparison to say other formats like a ring or a big open space, cage favors wrestling more.
In regards to upkicks, you underestimate how flexible and strong some fighters are. If a gassed wrestler is in your guard, its definitely feasible to do damage with them. Knees on the ground are a double edged sword. A failed takedown attemp could spell doom. I.e. when last night covington got sprawled on, jorge couldve done damage with knees. Lastly i dont think American wrestlers really have a killer instinct. They train to "grind" and control whereas the dagestani guys in mma are trying to do damage/submission. Regardless, all of the rule changes you mentioned would make the ground fighting more exciting.
Most people live in cities. And walls are literally everywhere. I'm surrounded by 4 of them right now. A ring is not significantly different, and I don't know how often you fight in big open spaces where no walls are near.
I think you just have very unrealistic ideas about how the human body works. When someone is in your guard, their hips are plastered to your hips. Your legs START at your hips. So even if you were tremendously flexible and could bend them above your butt, you have no room for momentum to kick out. And that's assuming that your opponent was sitting in your guard. If he's laying on top of you, it's physically impossible. Upkicks are rarely even effective against a non-grounded opponent, despite the fact that the extra space gives you much more room to maneuver and build up momentum in your swing motion. So if they're basically not at all effective at an effective range, there's no reason to think they'd be effective at a significantly less effective range. And I don't really care what some Gracie 40 years ago may have done because the game has changed since then drastically.
And no, Jorge couldn't have. For the same reason, you have unrealistic ideas of how the body moves. When you sprawl, your hips move backwards and your thighs and knees move backwards. This is so that your upper frame moves forward to counterbalance the movement of the shooter. Kneeing is a totally different motion. You can only knee someone if basically he is just lying on the canvas face down. But Colby never did that with Jorge, you can rewatch the fight. He was always driving even when Jorge sprawled, so if Jorge tries to move one of his knees forward, not only is it so close range that you probably can't build significant momentum on it, the moment you shift your weight the wrestler will push you back, and since you moved your knee up you're basically giving him your legs and putting your legs together, which is a guaranteed takedown. As long as he is driving and applying counterpressure to the sprawl, you can't change your position, Colby even took Jorge down through the sprawl in that fight, and it would have only been worse if instead he put his legs together. Yes, you can knee someone who is so gassed they're just laying on the canvas, but you can also take their back or head and arm and gnp or submit. Or even, if they're that tired, just let them up and piece them up on the feet. You're not actually describing a situation where the striker would have an advantage but doesn't due to the rules.
I mean, I would support those rule changes, but my point is simply that this idea that the rules somehow favor wrestlers is a myth.