Easy. Most coffee is made with anywhere between 1 and 2 tablespoons of ground coffee per "6" oz cup.
(yeah, they play games with 5,6,8 etc...)
In any case, the AeroPress needs ~3, at least according what I've read, or maybe even watched on youtube.
I'm assuming they are aiming for the "best" overall taste, otherwise anything less might not make the AeroPress worthwhile to use, let alone buy.
Any way, I ended up with a French Press, and an electric kettle to up the quality of my coffee experience.
The AeroPress would have been cheaper initially, but more expensive feeding it in the long run.
JMO.
I use 2 tbsp in the AeroPress with excellent results. There is an AeroPress competition, and I think the winners use about the same amount.