The difference is you could make things unrealistic or less-realistic but achieve more realistic overall results and the opposite, all things quite if not very realistic but still have completely random, if downright unrealistic results. It boils down how well the content holds itself together and how much it allows gameplay dynamics.
Say if they added slipping feature in RO2 and that russian boots tends to be less slippery and awkward in general on such surfaces it'd be perfectly realistic in physical sense but it would not really work that well in practice and would just be unnecessary doodling. Now let's say the odds are equal so the aryan in-universum avatars won't feel too much about it and it still would be quite unnecessary doodling, if realistic feature. Take suppression, a feature that is actually in RO2. How often do you see any "real" suppressive fire going on or even attempts to do so besides maybe the new players who might think it perhaps could work? Sort of realistic feature attempting to tackle one issue, but unfortunately in practice it's not really doing what it is supposed to do for fairly obvious reasons.
Bandaging. Ok feature on paper and in grand scale it would be realistic if bit out of place in the game. Now ok, I could live with that but since bandaged bodyparts\area becomes invincible to any further damage go figure. Sometimes makes it quite epic when you keep shooting your entire rifle stripper clip to that arm that was bandaged but pure aryan bandages to the rescue! (
RO1 wasn't (and still is not) perfect and there were things where it was absolute ****e as well, but it did have a spine to hold things together fairly well.
