Your wife's comment wasn't funny; it was pompous, pretentious and shortsighted. I don't play WoW myself, but apparently it serves as entertainment for millions of people. There is value in that -- if there wasn't, Blizzard wouldn't need nor could they afford all that hardware to run such "wasteful" software. WoW may not be feeding the whales or saving the homeless, but it's fun for a lot of people and that is something.
And if you simply can't sleep at night thinking what a waste it is, remember all the people who are employed to run and develop it, not to mention the people who made all the goods and provide all the services it uses. And all the technological innovation required to make it possible, a large majority of which was funded by and first deployed to the gaming sector, due to its lucrative nature. There's a forest among all those trees, believe it or not.