I understand where you are coming from with the changes, reducing the overall speed means that the game seems more realisitic but the height thing is stupid, yes it might make your animations look better but the point is that a player like Crouch or Zigic will be slower at turning than Lennon or Messi say, its real life physics, smaller players have a better balance due to a lower centre of gravity so they can turn in a more smooth fashion...Also messing with height means that players will be less likely to score headers due to there lack of height, also if you are lowering goalkeepers heights it means they are more likely to concede chipped shots...
If you lower the pace and make players smaller it means they will use up more enrgy getting around the pitch meaning their stamia will decrease and make them worse, which will also affect there passing which you want to lower aswell...