When I say shouldn't touch, I mean stories that wouldn't make sense to include or whose chance to be introduced has missed. This idea came about when they introduced Skaar which had me scared. This isn't a crap post on the MCU, this is discussing their previous actions, their patterns, & the effect it would have on these films.
For me, here is my list: (yes it's smaller because I know more about these)
Dark Phoenix Saga: This saga has always had a bad wrap & it was been done twice. I have ptsd on what Fox has done.
Avengers vs X-Men: This event is like Infinity War, it takes movies upon movies to build up to with establishing prior tensions & power levels. They already of Dr. Strange never defeat his opponent on his power so I know they're gonna do that with the X-Men; it is possible to get the idea of their power & water them down. They did this with Thor, Captain Marvel, & Thanos so idk why they didn't do it across the board. Not only that but they need Mutants that should not be introduced until years to come (like Hope Summers, which is by far the most important). They also need to accurately do the Phoenix Force's lore too.....which also took a long time as well. All in all, I feel it would be too hard to do with their current attitude.
Planet Hulk & World War Hulk: This is a matter of the window is dead & gone. Not only did the MCU failed to show Bruce's D.I.D. but it would make sense to do. For those who don't know, Bruce banner has D.I.D., his powers work similar to Legion. Bruce is the base personality, Savage Hulk (the one we all know) is literally a child; he's Bruce's toddler alter, & in Planet Hulk, the Green Scar was formed. This was a Hulk that spoke clearly, fought with strategy, & learned to have friends & allies. This personality was forged on the barbarian war torn planet of Sakaar. This could have been a girl boss movie too because there's a woman who quite literally back handed an angry Hulk. From this movie, WWH immediately followed with the ship he was sent away on exploding. He blamed the Illuminati & tore through the powerhouses of Marvel (Black Bolt, The Things, the Avengers, some X-Men, & Dr Strange) & fought on terms with Sentry. So there are too many elements that haven't been introduced prior & quite literally any changes made to the story would be = to that of Superman not being powered by the sun, or not being from Krypton.