The only innovative mechanics that I have seen from WOTC for d20 have been done on products other than D&D. Unfortunately (or fortunately), WOTC either leaves it for others to bring these mechanics to D&D or they introduce a half-assed version as OGL for others to fully implement. An example of the former would be the skill/feat system for magic (or psionics). The skill/feat system was used for the Force in WOTC's own Star Wars, but it took third party companies to bring it to DND. Examples of the the latter would be WP/VP, Class Defense bonus, and Armor as DR which were released as OGL in Unearthed Arcana. The attitude of WOTC was that they released this material as ogl, but they would leave it to others to fully implement into DND rather than doing it themselves. While I appreciate making these items OGL, I dislike the attitude that came with it. As a consumer, if I purchase a product, I expect the company to do the work and not leave it to me or another company to fully implement the system.