Currently, there are a plethora of Virtual Worlds supposedly created for the tween (ages 9-13) age group; ala Club Penguin, Webkinz, Neopets, etc. But upon further inspection, it is clear to see why the 7, 8, 9 year old demographic have a larger majority. There is a large difference between the social abilities/patterns of an 8 year old and a 12 year old... hence the differentiation of tween and twid.
Plus. Buzz words are cool.