Erik from Snap asks: "Why do you think it is so hard to challenge the status quo without rubbing some people the wrong way?"
Erik, you call it "challenging the status quo". I call it breaking the fundamental usability of the web. It's like having sites all in frames. It's like having popups. It's like Microsoft adding links to your pages. All in the name of "it's good for the user", when truly, it's not. Snap preview doesn't make the web easier to use. On snapsucks.org, it's compared with popups somewhere.
So to answer your question: when you break a basic user interaction (hovering over a link) and make it into something it wasn't (popping up a picture and advertising), you're bound to piss people off.
You're challenging one of the few things that really works on the web: the link. And I can't think of ANY startup (or huge company for that matter) that messes with the link that has prospered (although many have tried, and continue to try).