BlizzCon is only a figment of imagination...really.
Sorry - but I do not take online gaming serious enough to attend a gaming convention. If I had that kind of bucks to spare I would likely buy a new gun, vacation in Branson (which is high-speed enough for me), or any number of things.
HOWEVER - it is great that those of us who choose to attend can do so. If I were a professional in the gaming industry, I would not miss it. If I intended to write a book on how to WoW, I'd be there. If I had a WoW-related website which turned some bucks, definitely. If I took it serious in any manner, I would be there. I am sure a great time will be had by all those there...it just ain't my "thang."
To those who attend, I trust you will share with us what will benefit! And have a blast!