Okay 90%? Were we at the same convention? I saw at least 15 or so booths of anime stuff, or anime related merchandise (cosplay, hats, body pillows for God's sake, etc). I'm sorry you couldn't find what you had wanted, but this isn't Wal-Mart. Maybe they sold out or just didn't carry the series in their inventory ::shrug::.
I just copied the list of exhibitors into Excel for a quick count and there were 600 booths. There were definitely more than 15 anime-related booths there, but I doubt there were more than thirty or so. And frankly, you're sounding kind of rude here. I go to a lot of anime conventions, and I know that it's not Wal-Mart. I'd just like to be able to have fun shopping in the dealer's room, rather than pushing and shoving my way through aisles where I can barely breathe just to find that there's barely anything I want to buy. And if your experiences are mostly from comic-con like you said, then you're dealing with a different breed of con than the typical anime convention, so maybe that's why you can't understand why we all have issues with it.