Not to say that I am not aware of the fact that some things *are* directly borrowed from other editions of D&D (of which I include PF), but I think it's a bit unfair to categorize their efforts as being a hodge-podge of the available rules out there. Some things are relatively expected. As much as I am not a fan of the Vancian spellcasting system (I like power/spell points), it *is* D&D, just like the D20 is. Flawed but part of what identifies a game as D&D based. I don't think Pathfinder is ready to be not-D&D. If you don't think cutting away entirely from the D&D convention is dangerous, look at how some people LOATHED 4E.
However, from there, it's very hard to be completely original. Just saying, oh look, this feels similar to that doesn't mean that the devs went "how can we make 5E's BlahBlah work in PF2." My guess is that they are RPG enthusiasts so when they sit down and consider how they want to write a particular set of rules, it'd be impossible to divorce their ideas entirely from their previous experience in the field unless they specifically decided "we cannot do anything that's ever existed before." If they tried that, I would bet you'd get an even worse mish-mash of rules.
5E didn't try to reinvent the wheel. Didn't try to change D&D as we know it. It has a pretty simple plan, went through some awkward playtesting phases, and come out with a pretty solid product that was very end-user friendly. PF2 doesn't have to be revolutionary, just evolutionary, and I personally don't think it should just be PF1.5 because that's just not that interesting - I have PF1 already and have learned to control it's chaos, why should I invest in what I already have?
Personally, I think PF2 would be best suited if it was something with more meat than 5E (which is wonderful, but not complex) without being the morass of uncontrolled rules that made PF1 completely suited for only those experienced with it already or people who could devote hours each day trying to decipher it.
