Well, perhaps just one slice of the reason why.  From my friend Eugene:

I went to Best Buy to pick up [my girlfriend's] Valentine’s Day present …but realized en route that I had left the store pick-up notification in the printer at the office. After making a point of remembering it, of course.

I didn’t want to waste time going back to work for a piece of paper, so instead I pulled out my Eee PC at the 5th Ave subway station and managed to find a public Wi-Fi network–underground. I quickly retrieved the e-mail from Best Buy and walked into the store with it.

The guy at the counter was very helpful: “Anything for a Superman fan.”  And when Eugene was all squared away, he said: “Thank you for shopping at Best Buy. And for being a nerd.”

No one at Circuit City ever thanked me for being a nerd (or knowing more than they did about the stuff they sold).

The other amazing part of this story is that there is Wi-Fi underground somewhere and I do not know about it!