"Daddy! Can I quaff some coca cola?!" "Awwww.. must I wield the pjs??
" "Mommy..Mommy! Can we please have meat ration for dinner today??:" And existential problems when they leave the house and get dissapointed for the tenth time, that the world didn't get randomly generated this time either!
Nah honestly I think kids are good off playing roguelikes if they have fun doing it. They might pick up some english. It teaches them how to think strategically. (Kinda like chess) Plus it's a lesson of "don't judge by the looks, it's whats inside that matters!"
...plus your geek-friends will be mighty impressed when you can brag that your 11year old daugther ascended in Rogue!