You know, I was originally going to write some more about the ups and downs of announcing a new edition of D&D but really, who cares? Let's talk game design.
When working on 4e, there were a few principles that emerged and guided our work. I talked about one of them at the D&D Q&A seminar yesterday, and here it is for your edification:
Design game elements for their intended use. Secondary uses are nice, but not a goal. Basically, when we build a monster we intend you to use it as a monster. If we build a feat, it's meant as a feat, not a monster special attack. If we also want to make it a playable character race, we'll design a separate racial write up for it. We won't try to shoehorn a monster stat block into becoming a PC stat block. The designs must inform each other, but we're better off building two separate game elements rather than one that tries to multiclass.
As an example, the a theoretical minotaur PC race write up draws on and evokes the feel of the minotaur monster, but it doesn't simply copy over the rules.