Just a little, actually it would be interesting how it would play then. Sure, OW from high cover would then no longer go, but only in the direct direction of cover. I once took pictures*** of it (high rock as high cover), your line of fire goes up to around 45 °, up then you have a full field of fire, depending on what kind of cover there is in front of you (a tree offers smaller angles, a wall rather higher to shoot). On the other hand, such a high coverage in PP is also a high protection in the opposite direction with the same angles, straight ahead to 100% (apart from the fact that something shoots through the cover) and not just an accuracy reduction in the chance of hit (as in FXCom).
So, if you stand behind high cover like the big rocks, trees or walls, then you can already overwatch anything in diagonal direction to a certain degree. If the enemy wants to hit you, he has to go in your overwatch.
Edit***:
I found my post where I took some screenshots from the view of a potential enemy that aims at one behind a big rock as high cover: