l think the library scene achieves quite a bit, but a lot of it is either conditional or background material. That's generally thankless work, because while we all remember the big events, it's the groundwork laid out in smaller scenes that makes them resonate.
So to look at the library scene for a moment, I would say it does the following things:
- Shows the interaction between the MC and Bella in the wake of her spending the night with him [Conditional]
- Shows the friendship between the MC, Maya and Josy in the wake of their reconciliation
- Establishes that mild tension exists between Jill and Maya/Josy [semi-Conditional]
- Reiterates the point that the MC is going to take his studies more seriously in the wake of Hell Week
- Explores Sage's views on work-life balance
- Shows Maya is comfortable enough with the MC to openly flirt with him [Conditional]
- Advances the Derek/Wendy sub-plot [optional]
- Establishes future work opportunities at the library [Conditional on mini-games, possibly Bella path]
- Shows us more of Quinn's network, establishes Sally's role in it
- Gives us the return of KRJ!
It also theoretically gives us a lighthearted diversion in the D&G game (YMMV), which might conceivably serve as a bonding moment for the main cast at a later date.
So I do think the scene was important and productive, but it's all buildup (unless you like D&G enough to consider it the payoff). Beyond that, some of the best bits are dependent on pursuing Maya or Bella (or liking KRJ), so they may not apply to everyone.
It also drops the ball in a few areas, particularly involving Jill. She's supposed to be banned from seeing the MC, but you'd never know it from how she acts here; she makes noises about leaving, but she never does so and otherwise it's pretty much business as usual. Even the awkwardness of having the three girls together is just acknowledged rather than directly addressed. (Plus, it rings false when Jill has decided to stop seeing the MC, or when M&J are just friends).
So I think the scene is fine in theory, but the execution wasn't the best and placing the massive D&G sidequest in the middle of it called more attention to it than it was really suited to handle.