Not every series needs to evolve. NiGHTS worked perfectly fine before they added all other sorts of bullshit gameplay options. Mario worked pretty well before they wanted to make his game a buddy-platformer (like Banjo-Kazooie, Jak and Daxter, and Ratchet & Clank).
I just thought of what the game reminds me of, and it's a Spore video with Will Wright from two years ago. That's what interests me about the vehicle customization, that it works (or doesn't work) just how I design it. I think what worries some people, myself included, is that the world won't be the right size for vehicular platforming, that it will either be too small for vehicles or too big for Banjo to have any fun in. Even though BK and BT weren't all about platforming, there's a concern that the game will focus on strictly non-platforming events, like how Jak II did, or that the emphasis of on-foot platforming will be greatly lessened.
EDIT: You know, if there were more platformers out there, I wonder if this would be getting the negative attention it has been here. The genre has been somewhat forgotten since the end of the N64/PSX/Saturn era and the return of one of the defining games of that generation being so very different is shocking and disappointing to some people.
I'm kinda reminded of the Toon Link backlash from the initial trailer of TWW in 2001.
