I feel that's what made mission structure in GTA 5, and dare I say RDR2, kinda boring. it always has been "Oh let's start this all metodical, calm and collected.... NOPE, shit going down, everyone start shooting!!!!"""
While ranking system might not bother some, there will always be the completionist (no relation to that youtube) type of people who feel triggered by the game telling them "you did a shit job!". I the mission ranking system is removed, I feel people would care less on repetitve mission structure. At the very least, get rid of the mission timer.
Also, I am expecting a really good/hilarious writing. GTA 5 made me laugh super hard the first time I played it. It was a great way to distract me from realizing how streamlined some of the missions were.