Honestly, how often did Rory make a good decision? As far as I can tell, she can study. That's it. Translating her learnings into real life decisions was very hard for her.
The party was another "Rory is our golden child" in spite of breaking up a marriage, wrecking a car, and abandoning the town that treated her like a princess. No wonder Dean moved away (possible spoiler if you haven't finished AYITL yet.)
Luke's contribution of the party was another in a long line of (voluntary) servitude to the Gilmores. For a showrunner who apparently didn't know the last four words, Rosenthal