I mean of course people care about bonus episodes, more content of their husbands.
Joking aside, the episodes show the backstory and perspectives for each of the main cast in their respective routes. I think it would ruin the pacing of the game if the main story was full of incredibly long flashbacks for each of the love interests, that and there's clearly something happening for day 14, so there's no time to fit all the side stuff in the main story since as of now there's like 5 days left for shit to hit the fan