I agree, its a valid point, aircraft for example, take time to accelerate, but when you lower their speed it slams straight down to whatever you set (925knts ->350kts in less than a second ) so if acceleration is modelled, albit probably simply, why not apply the same mechanic to deceleration?
It might not make any difference tactically, but then, it might just. You ever been micromanaging a dogfight and tightly controlling your speed? It could have an effect there. Less so with ships and submarines, but the point is valid.
The devs will focus on whatever they think is most important, whatever we discuss here, after all this is all just text.