Sometimes it's fun to apply vaguely UX thinking in terms of things like game design...
His design rules for Mega Man 2 were specific and deliberate. Enemies appeared in small waves, three or four at a time, using the same attacks, so players could actually learn the pattern. Terrain and placement adjusted the challenge, not random enemy behavior. And here's the detail that reveals everything. The last enemy in each wave was easier than the ones before it. I'll say that again on purpose. The final enemy in a wave was easier. Why? Kamura explained the psychology this way. He'd notice that people don't replay games, even good ones, because when they think back, their minds go to the hardest parts, and that memory makes replaying feel like work. He didn't want players remembering Mega Man 2 as a slog. He wanted them to remember feeling like they were getting better. And then he said something that is essentially the entire point of this video. I quote, "I wanted the player to feel like he was improving at the game, too."
Although it calls out "Battletoads" as being brutal relative to Mega Man in part because of having 3 continues / no passwords (along with punishing "gotcha"/ MUST memorize design) it underplays the addition of continue password grids as being a HUGE quality of life improvement in Mega Man 2 over 1.
I remember my pride in beating the original "Nintendo Hard" Mega Man, telling my mom about it - an early lesson in standing up and getting through a big challenge.
Also I think about Mega Man in the sense of novelty. Not only was it a master class in terrain and enemy placement as "something new", but of course it was one of the first to give you an array of weapons with different mechanics. Later games (such as Kirby) would expand that so that it let the player control novel mechanics and interactions (often by capturing those of enemies) as the game progressed - now it's one of the biggest tools Nintendo has, from Kirby's inhales, to Mario Oddyssey's Hat Capture, the new animal transformations, etc.
So there probably is a split - most games provide some kind of novelty as they progress. Some games, like RPG, it's gradual and cumulative, and intrinsic to the character or the inventory. Other games, it's closer to a temporary toy (or in the case of GTA, knowing where the good toys are.)
