Perhaps this is one of those things where FDev could take a leaf out of Kerbal Space program's book?
Squad started off by setting KSP up so the atmospheric flight model was "in place" but a lot of the variables were set as constants or switched-off completely.
That way, the system was in place but not really doing much and then, with each subsequent update, they could tweak things like the drag model and air density, and enable additional things like friction and stability.
The big problem with ED is that there's a huge variety of planets and, due to the procedural generation, it's entirely possible that FDev won't even be able to predict the full range of requirements that are necessary.
I mean, you might set it all up so that flight is straightforward on anything up to, say, a 2g planet and then things get progressively harder for planets up to 6g.
Trouble is, then you're going to find there are planets with 8g and a lot of the ships just flat-out won't fly there.
So, you adjust the envelope so that ships can just about fly on an 8g world.
And, by doing that, it becomes much easier for ships to fly on more "normal" planets, thus undermining your original intentions.
Course, this could provide yet another opportunity for diversifying the roles of the ships.
Your Cobra 3, Viper 4 and AspS might currently seem very similar but they might have entirely different aerodynamic characteristics which means one will be the best all-rounder while another one is suited to low-g worlds and a different one is best for high g-worlds