The other points here are quite valid, but I think they miss the reason why legal scholars disliked Prop 22 so much. It requires something like a 7/8ths majority in order to be amended? It was effectively a statute trying to backdoor as a constitutional amendment.
Apparently the 7/8ths thing isn't so problematic in itself, as other ballots don't allow even that. The bigger problem is that they prevent the legislature not just from overturning prop 22 itself, but from passing other laws in this area that are not aligned with it. This is the part the judge understandably took issue with.
