There are pros and cons for either demographic: whilst being older may be ideal since not only you bypass age restrictions, you also have the capability on purchasing it with your own money without having to ask parents for that given that you have employment and recurring income. Gaming as a kid gives more time without having to dwell much on responsibilities that adults have to worry about but at the same time are held by school.
I mean when i was a kid i struggled to get double digit fps in ironforge, but now i struggle to get that same sense of wonder from ul’dah. But also i actually have more than three games so i pick adulthood
Ul’dah is still pretty cool, though.