Actually the CRLs are a reference, the base standards are actually lower than the CRLs text. This is being looked at from the wrong end. Instead of lower and lower standards to should be seen as higher and higher with encouragement for troopers to achieve instead of looking down on others. Some on the FISD are at the top % of what's possible and it's unrealistic to have a program that is that high.
If you look at the SLD program there is for Vader the base standard then for the first tier you have to have one major and one minor upgrade, and for the second tier it's three major and minor upgrades. The Vader I got approved already meets the second tier and then some witch isn't difficult to hit if you do your homework, but the goal is getting people to make a few upgrades bringing up the overall level on a broader scope.
The goal of centurion is not prop replication, it's between EIB and prop replication while staying within the confines of what is 501st acceptable. People need to stop with the assumption that just because an actual prop was done this way makes it Legion acceptable is not correct. You have to remember the 501st is a costuming club not a prop group.