Why?
Dubya should never have been President, the game plan drawn up in 1992 was for Jeb to win the Florida governorship in 1994, and serve a full term, before being nominated for the Presidency in 2000. But Dubya won his election in Texas, and had a full term under his belt, while Jeb was only in the second year of his first term, as Jeb had lost to Lawton Chiles in 1994, by a very narrow margin (considering this was Florida, probably an honest count would have tipped the election to Jeb).
Jeb is WAY smarter than Dubya, and a whole lot more serious. Not to say Dubya is not himself quite intelligent, just that Jeb is both quicker and more composed in his thinking.
But the moment has passed. The opportunity that existed in 2000 no longer applies, and the demographics have simply moved on beyond any stepping back in time.
Democrats can blame the "Bush nightmare" on Lawton Chile's massive ego.