It would make good sense, there are several advantages:
!) Obviously, by avoiding placing emphasis on playing catch-up on DDR2, which has limited advantage right now anyway, a great deal more resources can go to DDR3.
2) DDR3 should debut before DDR2 gains any real advantage on DDR1.
3) Taking an early, active roll in DDR3 will place them in the lead when it comes to the PC.
4) Lower power consumption Will give AMD a leg-up on the notebook market and among the heat-conscientious, such as power-users.
5) If they can implement some sort of backwards-copatibility with DDR1 they can leapfrog DDR2 altogether and offer a superior upgrade path to those prone to seeking such a path, such as power-users.