Why the glass should be half full

I recently attended a masterclass given by Austrian Georg Riedel, on the art of choosing a wine glass, and how to use it. I sniffed and swirled, chewed on white and dark chocolate, and, after, tasted red wines from three different types of glasses.
I also, separately, tasted water and white wine from the three same glasses, which were designed using scientific analysis of the DNA of many of the 1,200 varieties of grape.