I really appreciate you taking the time for a full response! I definitely agree that the kill count would spike hilariously, and you're going to end up with massive characters arriving in lane with a full complement of tools to abuse their lead. I do think the gold/exp rewards for killing level 3 champions could be tuned even further downward, but that might break player expectations and leave players feeling shortchanged when their score doesn't match the expected reward.
But I disagree on the value of the level 1 fights- it's a kind of problem solving that's perfectly unique to URF, and something that definitely evolves and balances itself as a micro-meta evolves, but I don't think that's best for the general player experience right now. There's a possibility that the balance and playtest teams (and to a lesser extent, PBE community) are more experienced and knowledgeable about the general power levels and tactics, so they're reporting a more fulfilling experience than someone who just wants to play the hyperspeed version of their main.
Metatextually, I know player counts spike during worlds as inactive players return or seasonal players return to their migratory nesting grounds, and I don't know if that kind of depth is going to be as fun for them. There's a lower- I don't know how to say this, but "ranked anxiety" but for League as a whole. Coming back after a long break is sometimes emotionally taxing, trying to catch up with the meta and champion changes so you're not a burden on your team or a target for abuse. URF, and rotating game modes, are a "lighter" experience, which I think is invaluable given the universal anxiety in the state of the world. I think there's more value in reducing that crystallized knowledge burden.
If a fed enemy is abusing you with their three abilities, I think there's at least an understanding and fairness to that spectacle. Their power matches their identity- Maokai's more than just sapling artillery, Akali is more than an immobile DPS lawnmower. At least you're getting smacked around by a familiar face.
I agree that it's possible to communicate to your teammates to back down from the toplane brawls, but I think it can be emotionally draining as well. I think there's some evidence here of community frustration with the current state of brawls, but also plenty of people interested in preserving the ritual of the thing (which I am 100% for! if that wasn't entirely clear). I love that idea of dumb rules we all obey, but I don't find the experience fun when I'm playing a character that's at a distinct disadvantage level 1. When tower hugging is unilaterally the best choice for the character I want to play, and my teammates are positioned to railroad over the enemy, there's an inherent frustration and conflict involved. I will absolutely feed my ass off if the rest of the team is fighting, but it's more for moral cohesion and keeping everyone happy than any strategic reason. I truly think we could all use some more levity in our lives right now. There are other avenues for players to puzzle away, suss out personalized optimizations- in TFT, in the upcoming item rework, in the primary SR experience.
I fully admit that my opinion here is skewed by my personal frustrations. Honestly, my main motivation here is that my brother and I have had a hard time finding a game to play together since he moved away, and I'm having trouble convincing him to play League again because he becomes frustrating for all the reasons I've mentioned. But I would really, really appreciate a hard Riot brain-trust group thinking session on the potential merit here. Really- thanks for taking the time to respond!