In regards to the "positioning" of infantry units vs. grenades. The amount of "clickiness" or "micro" that the use of grenades adds is negligible unless you are in the mindset of "I'm going to send my infantry to this cover here and they should have the advantage". Instead think ahead. OK so if I move my infantry to this light cover first, wait for them to throw a nade, then move to the adjacent green cover, I'll be have the upper hand as I'll have lured them into wasting munitions and I'll also be in superior cover. As opposed to moving them into the green cover immediately and trying to fight it out from there.
The purpose of a grenade is to flush troops out from cover (hopefully killing a few in the process). Cover in this game is directional also, which means if a rifle nade lands on the side of the cover your guys are on, that stone wall isn't going to stop those metal fragments.
The only thing grenades add is tactical depth to the game. God forbid you have to click 2, 3, or 4 more times to dodge them.
I have written more about this previously. The point is, cower dosent matter much anymore, so there is little to be gained by flushing enemies out, because the few seconds they spend out of cower really dosent matter that much. This goes both ways. In vCOH, an enemy in green cower would be a serious threat, and charging him through red cower would be costly. In COH2 you just run up to him and throw your grenades, and then you both dance arround for a while.
Understanding and utilising tactics, and the chess aspect of COH becomes, less important, and moving about "casting spells" is more important. Personally, I really liked the tactical depth and realistic twist on combat, and im sad to se the importance of understanding basic tactics toned down. I always enjoied COH because it challenged my mind and strategic abilities, not so much my reflexes and mousemovement, but I guess its a matter of taste.