Adult's Eating Children's Portions In A Restaurant

I was listening to the radio yesterday morning on my way to work and they were discussing adult's eating children's portions in a restaurant.

It seems that this is frowned upon, but why? I mean the restaurant sells a meal still, the customer actually gets what they want. Sure the meal may be cheaper but would they rather you get a cheaper meal than not have your business?

Some of the place's I have been to have proper good children's meals as well. Sometimes I'd rather have that but haven't because the portions are smaller. Maybe I'll just buy 2 portions of the children's meal. This way I get what i want, I get the portion size I want, the restaurant gets just as much money as if I'd bought a adult size portion, so what wrong with that?

And why do restaurant's sometimes have completely different meals for kids? It's like they are teasing us. I mean look at happy meals, why the hell don't I get a toy when I pay way for for a Double Quarter Pound Cheeseburger? Would be great for work, easy to play with the on the desk.

Maybe I'll make my own restaurant where all I have is kid's meals and adult's get double for double price or something. make it fair for all :)