If I were rewriting d20 Modern today, I'd hybridize it with the Cortex system games and try to create something a little less hackneyed and more of a simplistic reality simulator.
In short:
*Get rid of BAB and saves and make everything a skill.
*Make a set list of basic skills that advance a finite amount, followed by an open-ended list of subspecialties.
*Flatten the math enough so that ability scores are always relevant.
*Get rid of classes and make it strictly point buy.
*Covert feats into the point buy approach.
*Add in active defense and a more robust action system.
*Get rid of hp and replace them with something more naturalistic and more deadly.
*Add in a bunch of modules for specific genres and settings.
*Get rid of the spiky-haired art and redo the tone of the book to something more appealing.
*Keep most of the basic skill/feat/combat mechanics as they are.
Then we'd have an rpg worthy of the title "d20 Modern".
