Actually, Nash *DID* run pick-and-roll a lot with Marion - during the year Stoudemire was out. That year, Nash/Marion was the typical pick-and-roll, with Diaw as the out man because of his passing.
WayOut has the idea - personally, I double the roll, and in doing that, I force Kidd to shoot. If he tries to drive, he's driving right toward his defender. Going under the pick is also valid, but even so, I'm helping on the roll rather than worrying about Kidd shooting.