In some ways Booker (at least from a left-wing perspective) would be even worse then Hillary. He'd probably campaign openly and unapologetically on support for TPP like deals and would essentially represent the complete realignment of politics where the Democrats would become a fiscally conservative and socially liberal elite party and Republicans a right-wing populist one.
Plot twist: Booker voted against fast-track.
I swear, the caricature of Booker on this sub makes it appear that he's to the right of Jim Webb. There's little in his vote history or as mayor of Newark to indicate anything less than a progressive record on every issue except education reform.
He's pro-free trade, which loses the industrial areas. He's a transparent Wall Street supporter who defended Bain Capital publicly, which loses progressives. Dressing nicely and speaking well aren't qualities that necessarily make a good candidate. He needs to be able to fire up the progressive wing.
Oh and the education thing isn't going to endear him to many