If already 80% of players don't usually finish the main story once (and their games in general), does it seem weird to think that they could redo these missed quests in a second playthrough when they never finish one at least ?
No chance that the majority players will play a "next one"
So like
@Bealdor said, missable content is a waste of work/money/ressources for at minimum, 80% of the players
For example, KCD, there are quite a few missable quests that you maybe can redo in a second playthrough (obviously what i did). But only 3.99% of players finished the game once... So for 86% of players, I imagine that the missed quests are just equal to "no content", they won't play it again...