This is Google's search team we're talking about here. They might make the mistake of overestimating how much people will like something like this. They might make the mistake of underestimating how many resources something like this will take. However, they simply don't make mistakes of the kind you're talking about. I'd be willing to bet money that there's a bullet-proof theoretical model behind what they're doing. And they probably aren't ready to talk about it yet.
Except that I named two areas where they can make mistakes. And Google's success is indeed because of the hard work they've put into building such a smart team of search engineers.
