Well I'll be honest, I don't mind you not being able to use a uniform off a dead soldier. Think about it, you are going to draw a lot of attention if you are walking around the base with a uniform that is riddled with holes and covered in blood. So that's pretty realistic.
What is better is to have a situation where you can get uniforms to use when you need to but do it in a realistic way. Like allow you to get to the barracks at night where you can pull some uniforms off the clothes line like in H&D 1.
Another way they could do it would be to keep track of where you shoot the person. Make you kell multiple people to get uniform parts that aren't shot full of holes. Then turn them over to a resistance fighter who has his wife clean them.

But that would require some serious coding.
I guess the best way is for there to be some unused uniforms in a tent or cottage or barracks that you can commandeer, or just have a resistancee fighter give you the articles. Or have them available in the loadout screen. Not unusual for an operative to be given a uniform ahead of time if he needs one to complete his mission.
For the captures, they could have just made an animation for the guy to call out to a patrol if it came near. Then have an animation for them to untie him. Then one for him to pick up an unused weapon and join the patrol.
But then it's not really a huge issue.