A tall CDM is just my preference. Overall it is not super important to have a tall CDM. I just like having them for situations such as when you are a goal up and the opposition is pushing hard at the end of a game for a draw. I find it better to have one or two more players who can head the ball out of he box if there is a cross to be valuable for my team, especially if my CB's are out of position. I do agree with your home grown player model, it makes the game more realistic when it comes to scouting players both for transfers and for your youth academy.