Because Google was such a great name? If you don't know what a google is, the name sounds even sillier than Bing. If you do know what google means, it still seems like a very silly name for a search engine.
I'm not sure how it's going to work for my most common searches (all having to do with software development), but it looks like a dream come true for the average "consumer search". Unlike Live Search, I'm sure I'll use Bing fairly frequently, even if it
doesn't become my default search engine.
But Google means nothing so you can turn it into whatever you wish. Kumo might have been the same way.
Plus attacking Google isn't really a valid defense of Microsoft's new name and constanting rebranding every two years...