>>109783167It's a natural progression of her characterization. It fleshes her out beyond "protagonist's BFF".
Alya was a good person in the first season, and she still is. But her thrill-chasing has to be addressed. This is the girl who gets herself hurt, repeatedly, because she doesn't take akuma seriously. This is the girl who ignores the one wish of the people who saved her life.
All those things boil down to the lesson that I'm sure Lila is going to teach Alya: she has to THINK about situations before jumping in and making assumptions.
It's no coincidence that the reason Marinette couldn't pawn off the LB Miraculous on Alya was because she was busy recklessly going after danger.