You're arguing that style (how features are presented) is more important than substance (the presence of features themselves) and I couldn't disagree more.
Again no, I'm not. I'm arguing that having the feature isn't enough because they inherently aren't realistic nor immersive. I'd rather have a game built around having lean or prone as opposed to just having them tossed in after the fact to appease people like you. And yes, in terms of gameplay there is a huge difference between those two things. Implementation means a lot more than simple presence of features and implementation affects immersion significantly. I couldn't spell it out any clearer unless you want some crayon doodles.
Playing: Fallout 4, Warhammer Vermintide Watching: Ash vs Evil Dead