Can you imagine what will happen to Mozilla if Google stops the contract?
IMO, it is just a strategy of Google. First make the Mozilla heavily dependent on it and later ditch so the Firefox can easily die
I'd guess about half of my searches go like this:
* type into URL bar * get Bing result * after a quick glance: decide that result is useless * copy/paste into Google
I'd love to use Bing almost exclusively (especially since I'm really happy with my Lumia 630), but it is really frustrating sometimes.