Useless? Everything looks much cleaner on the Retina display. Every web page you go to with imbedded video, photographs, or HD graphics are much improved with the Retina display. Apps look sharper, your personal photographs, etc...
If all you're going to use your Macbook/iPad for is typing and reading text, then the Retina display would be useless.
If it were useless, people wouldn't have been clamouring for Apple to release an iPad Mini with Retina display. It also would have never become the standard on all the other iDevices. http://www.imore.com/ipad-ipad-2-retina-display-tests
Maybe useless isn't the correct word, yes retina is better, I have an iPhone with retina and Iove it, but the quality of non retina monitor is just ok for eveything I do on the lap top, and I am no an eagle eye.