It's interesting. I thought the "secret push" behind this set of poll questions was "How would you feel about a single iconic character?" And I think this ties to what they were saying overall about the brand of D&D with previous discussions about the logo, about possibily having a non-logo icon (ala the "dragon swirl" at the top left of the Next character sheets), etc.
My guess is that they want to use Elminster more heavily, as a "front of the DMG" type character ala some of the 1e books. This is based on the 1 character assumption above, their seeming renewed focus on Forgotten Realms, and the fact that the wizard character may strike them as the most uniquely D&Dish.
(Though to be frank, if they were going to pick a single iconic, I think a rogue/thief is more iconically D&D. It's the iconic dungeon crawling, kill 'em and take their stuff character class. The guy who's prying out the statue's jeweled eye is a thief, not a wizard.)
Ultimately, they can do whatever they like with this. I don't know anyone for whom this is makes a serious difference either way. But my preference (as with a lot of things) would be to use a similar approach to what was done in 3e.