8 wonders why the "Install Font" dialog looks so old-school. (And Kevin Provance demonstrates poor reading skills by not only ignoring the paragraph that explains why the suggestion box is closed, but also asking a question that's a dup of one already in the suggestion box!)
Because it's a really old dialog.
That dialog has been around for probably two decades now. It works just fine, and since it's not really a high-traffic dialog, updating it takes lower priority than things that get used more often. Development and testing resources aren't infinite, after all. I'm sure that if you look harder, you can find other old dialog boxes. (My pet ugly old dialog is the Character Map program. It's hideous. and I say that even though my boss's boss wrote it.)
Besides, people don't really add fonts that way much any more. When you install font packs, such as the Consolas Font Pack for Microsoft Visual Studio 2005, they just install the fonts as part of their setup process. It's all taken care of for you.