Delta-1138 said:
well jumping out of cover will not exactly help you either if you want to dive behind a wrecked car, au contrair, it will probably ensure your imminent riddeling with bullets of various calibers.
yes i mainly play multiplayer, but the point remains valid in singleplayer. there are moments where you simply have to go from standing to lying down instantly or you are hosed. having a button for that isn't exactly rocket science.
that said, i saw a script not to long ago for exactly what you are describing: pushing the button to crouch, holding it for x miliseconds to go prone. it was nothing complicated, like 4 lines of cod script language. i'll see if i can find it.