The point of the model isn't really to gauge accurate DPS measurements, but rather to get an estimated average DPS to calculate statweights. If you remove the (1+0.1*20/80) from the equation, the weights will all remain the same. Model is only there to get stat-weights and aid gear selection, nothing more really.
The only difference is the Hawkes Eye Buff which is a direct influence on Dexterity. That for sure, will affect the weights.
If you wanted to get a much more realistic DPS number, then you'd need to actually make a fully working simulator which can simulate DoT fall offs, optimal cooldown usage and whatnot. The weightings will not change however. (Except for the Warrior)
