As to your first point, these sides scrolling multiplayer Marios seem to all suffer the same fate, at least with 3-4 players. Two players is a little easier. The camera just isn’t built for players to be all over the screen and have it keep up. And, it wouldn’t work either to have each other simply completing a section one after another all the time. It’s certainly not how people envision playing together, yet find out quite quickly how the are forced to play together. I think these games still shine the most when playing them solo.