Perhaps they want you to say Oh, I've found it (just think about what you might say when you've found something, a word beginning with Bing). :sarc:
Not a very inspiring choice of name, is it? I prefer things to be called by a name which implies what they are. I can understand the word Search being replaced by Hunt, Find, Seek, Look, Trace as these convey the same meaning. Bing, however does not convey any meaning whatsoever. I know that Google isn't an obvious choice for the name of a search engine, but over the years Google and Search have become synonymous terms, and people understand that they mean the same thing (just like Hoover and Vacuum Cleaner).