If it's nearly impossible to make a satisfying sequel, why are you surprised? That comment makes no sense to me.
John Wick 2 was exactly what I hoped it would be: it stayed true to the original. Remember how people didn't like Iron Man 2 and Iron Man 3? Those movies were true to the original. So I have to question a person's agenda when they walk into a sequel. Do you want it exactly the same as the original? Or do you want it radically different? Sequels don't bother me, and if you look at Captain America: Winter Soldier, there's a movie that's vastly superior to the sequel.