It's nice to have alternatives for something that's so fundamental to how we use the internet.

Google works well today, but what about 5 years from now, or 10 years from now? What if you need to be signed into Google+ to Google search? What if your Google+ account needs to be tied to a mobile phone? What if Google has limited search, and you need to own a Chromebook or Android device for the full search experience and viewing more than 10 results?

Competition keeps them in check from doing anything outrageous, and then if they decide to anyway, we have other choices we can migrate towards.