I'm kinda with ShredNJ on this one i think, im not gonna assume to know all about footbag history etc but it is exactly that- history. If ADDS were created to define Difficulty, and the system has now evolved into something different, then you cant really go and try and change it back, can you? I was always told and under the impression that, Adds defined the components of a trick in order to describe a move textually so that anyone reading it could understand the move without a visual demonstration.
We know that Adds dont describe difficulty, as the Frigidosis example highlights, so to try and create another Add component such as Flexibility is really just giving brownie-points to ppl who can do the moves (no disrespect obviously to anyone who does this stuff, i know its shit-hard!

) So then Dragon is just a cross-body unusual surface, so it gets 2 adds, and Doof is just Unusual surface, so its one add.
When u consider it, everyone knows how hard moves like doof or frigidosis are so u get props for hitting them anyway, so adds shouldnt really matter.
But of course this is MY OPINION which im entitled to as is everyone else so lets not start another Flaming match