Impulsivity, please get some variety of degree or other qualification about this before you open your mouth, or at least check wikipedia :P
"I can't think of anything anyone could learn from Brain age for instance. It does indeed use thought, but it doesn't teach any skills/knowledge. There is a difference between trying to pop balloons in numerological order quickly and learning about the History of Germany from Carmen San Diego."
Correct, there is a difference.
Memorising facts is recognised as the lowest form of learning or brain development. Just because you can't express to a friend what you have learnt, it does not mean that it isn't increasing your mental capacity. Brain Age or Professor Layton and the Curious Village (3rd party DS) is what I would want in an educational game.
Unless I wanted to learn something specific, like a language. Oh, but Nintendo make games like that too :P