Well, it's got to do with brand labeling and there's some other fancy schmantsy term too which involves bringing up kids to think it's the ants pants.
For example, they have those play gyms and stuff there and 'happy' meals etc and pretty much everyone has said something along the lines of, "I'll take you to mcdonalds for a treat" to their kids which means kids are brought up thinking that it's a place you feel happy being at and eating at.
Yeah lots of people 'outgrow' mcdonalds food, but some people never grow up.