Do We Really Not Know Obama?

I don't really understand this notion floated below by Glenn Loury and (to some extent) James Pinkerton that we don't really know Obama. Loury points out that Obama has rounded off the edges of a lot of his arguments so as to appeal to as many people as possible and thus has the left the nation unclear on what he really thinks. Isn't this what politicians do? How many presidents have published two memoirs of their lives--before and after getting into politics? How many presidents have confessed to drug use? As Jamelle Bouie points out, there's even the David Remnick biography (which Barack Obama was interviewed for) laying bare the man's entire life. 

I don't really get it. My sense is that Obama is center-left president trying to cobble together the largest coalition possible to support his agenda. That's what center-left politicians tend to do. And then making the case that Obama is somehow responsible for Dinesh D'souza racist scribblings just seems untenable to me. This propensity to struggle with the fact that president is black is not confined to the Right.