Not to mention that the whole party was there to drop hints and clues for familial relationships and then drop a big giant plot bomb at the end.
Also, it was a fun party with lots of character interactions, which this whole game has been about from the beginning.
Every update has had one or two key moments, surrounded by lots of character development. Some of those key moments took longer than others, especially in the first 1999 segment, but none have been dominated by the moments over the character development.
So if you finished this last update and thought "The dev suddenly doesn't know what he's doing, this was all filler" why are you still playing? You should have dropped out long ago.
Based on the idea that this chapter was "all filler" then the Skylar date was pretty much all filler -- both of them actually. Watching TV with Tiffany was filler. Helping Jessica with her camera was filler. Speaking of camera's, the photo shoot at the boutique was definitely filler. Working on the class project with Alyssa was filler. The time at the lake with Scarlett was filler. Practicing lewds with Darci is filler. Exercising with Valerie and Tiffany is filler. Also the challenge in the jewelry shop is filler. Spending time with Krystal is filler ... pretty much all of it except the stuff pertaining to the blackmail, so ice cream date is filler. Most time spent with Jenny is filler -- playing on the computer, in the arcade, messing around on the car. Pretty much the only parts of her story not filler would be the times trying to convince her to not work at the plant -- although how you would accomplish that without building a relationship first is beyond my writing skills.
And that's why the whole "filler" argument is so stupid. NOTHING in this story works without the MC developing relationships with all these people. And the party was the latest part of that. If the party doesn't happen, Luna doesn't get so scared of the MC that 20 years later she drops the "ANYONE BUT HIM" bomb on Skyler, completely changing her story going forward. ... an event that has been set up since we first met her.
So yea, all you "filler episode" people are clearly playing the wrong AVN for your tastes. I suggest trying something else.