Why do they make kids pajamas out of that nasty cheap material that pills?

When I buy my son pajamas I always look for the 100% cotton, non-flame resistant kind just because they wash up so much nicer. But so many of his that he's gotten as a gift, the ones with the cartoons on them especially, end up feeling like this god awful rough stuff that feels so nasty. Why do they do this to kids? How many kids actually catch on fire due to their pajamas every year?