As one of the three lonely supporters of Creeping HEROization

, there's one thing I'd like to see brought in that I think would help the game's flexibility immensely and reduce some of the complaints that have been made against 3E--specifically, the emphasis on gear and complaints of 'cookie cutter' builds.
Effects-based balance.
Give us about 6--12 pages on the various roles in a party--there appear to be four basic ones in D&D, Warrior, Arcane Caster, Divine Caster, and Skill-User, although you might be able to break the last one down into Social, Wilderness, and Rogue/Dungeon-Crawler. Explain how each class in the game fits into those roles, and what each of them should have for stats and capabilities at a given level, in a general sense. I.e., a 10th level Warrior Type should have a BAB and AC in this range; a full-fledged Arcane Caster should acquire the ability to fly at Level X, but should not be able to use it more than a few times a day until Level Y, etc.
Then let the DM determine how to reach those goals in a given game. The 'default' is through a combination of experience levels and equipment, but DMs may wish to reduce the importance of equipment by increasing class abilities and reducing treasure to compensate, adding bloodlines or templates, or completely redefining the whole character advancement paradigm. Notes on the boons and drawbacks of each method should be included, of course--equipment can be stolen or destroyed more easily, but can also be loaned to other characters and used in the event of a character's absence or death. This would also make the CR system more useful--if we have an example of what a typical group
is at each level, it gives us a clearer handle on what 'a suitable challenge for a party of X level' actually
means.
Now, I haven't kept up very well with the d20 market, for a variety of reasons, so maybe someone's already done this. But I think it's one case where an effects-based approach would be a real benefit to the game.
Matthew L. Martin