I wouldn't mind if they introduced popup damage as an additional option - strictly for those people that want to test out weapons, check various loadouts or differentiate between builds. For regular gameplay it would be more like Borderlands and i wouldn't want that personally.
As much as this game is configurable, such "visual" options could simply be options, just like there is a mod that shows an HP bar for enemies, there could be a mod for popup damage, more sneaking incentives or whatever.
From my long time experience as a sneaky bastard, it's very viable and doable even for the biggest POIs and toughest enemies.
Perk up, train and succeed you will.