As for the idea you are purposing, it is a valid one. Players performance attributes are what matter, not their physical attributes. Height does help with jump balls, weight does help with taking up space, but it is not directly tied to players performance attributes.
Also if you want some valid class data (this is not dynasty exports which use grades, but there actual attribute data) check out the file below:
http://www.pocketscout.site90.com/files/BigList.xlsx
EDIT:
I like the idea you bring up, but at the same time I do hope that if anything is implemented, that it is still done on a bell curve like the rest of the play attribute distribution. Most of the guys would fall right in line, but this way it would still leave open the chance of a freak like Brandon Jacobs to be generated.