This argument isn't true at all. What if the child wants to change the file associations? What if the child wants to draw a simple drawing? ( Paint brush kicks Kpaints a$$ ). What if the child wants to install a flash plugin? Firefox has issues installing plugins on my FC5 system.
Who knows? The child might just solve all these problems. eg., she might come with a KPaint that kicks Paint's a$$!
IMHO it is much better to expose a child to things she can do, than stuff ready-made for her.
Regards, Debarshi