I could submit a patch adding hooks to core to enable all of the things (or even just some of the things) that EnterpriseDB has changed in Advanced Server, and that patch would be rejected so fast it would make your head spin, because of course the core project doesn't want to be burdened with maintaining a whole bunch of hooks for the convenience of EnterpriseDB.
I can imagine that many such hooks would have little use beyond PPAS, but I'm somewhat curious as to if any would have wider applications. It's not unusual for me to be working on something and think "gee, I wish there was a hook here".