Yes well, people on the internet (people like bose) need new stuff to play with after some time and they come up with this. It will keep them busy for a while.
Having 4 googles in a single page makes it much easier and faster to work. And you can also choose to browse any page other than google. It really makes searching for several things at the same time much easier and faster.
Having more than that in the same page makes everything a mess. But some people just have too much free time....
Actually you're right, but some people just can't stand changing tabs every time they want to go to another website.
And by the way, in my opinion things are easier and faster if everything is in the reach of your eyes at the same time. Of course you don't need a web page to do that, but anyway...
Click for full size
Not all browsers have this function. So, at least in my opinion, the googlegooglegooglegoogle website is useful.