Good points, yes. Plus not having Robert Duval in “3” was a big loss.
I’m fine with the 3rd GF movie. But it probably suffered from being made too long after the 2nd. Strangely, the actors were 15 years too young to be playing their roles in the 3rd (which was supposed to be set almost 30 years after the end of the 2nd). The most heartbreaking scene in the 3rd was the one with Michael mimicking the death scene of his father, but this time, there were no grandchildren.
I thought not having Clemenza in II, was a loss as well. They basically had to invent Pentageli to cover for not having Clemenza.