If the cutscenes in SMS were skippable, how much time would we save? I'm astounded that it isn't already possible to skip them.

Uhhhhhhhhhhhhh there are already cutscenes you can skip, for example

It is indeed astounding that Nintendo decided not to make cutscenes skippable. Unfortunately it's not always possible to break a game to the point where you can just do whatever you please, as is the case with this game :)