I don't mind bosses not being susceptible to all status effects, but I do think which can be used should vary from boss to boss. Death/petrify/etc would make the game too easy, but most other effects I think should work on all bosses. They should just program the bosses to have counters/ways of healing certain effects to keep the difficulty up.

One thing I hate is when you can't analyze bosses like in Persona games. it makes no sense to me and just adds a little bit of tedium to the fights.