I was a picky kid. There wasn't a lot I'd be willing to eat for breakfast, but cereal was one of them. I craved that hit of sugar in the mornings. I still do, though I realize that a bowl of cereal is not nearly enough to keep me sustained for more than an hour. Somehow when I was a kid, that didn't matter. I don't blame my parents-- they did try to pick out the healthier cereals so I would at least get a little fiber, but I was a kid and kids can be picky.
But you can't let them fully rule the roost in terms of what they eat. If I was given completely free reign, I would have eaten nothing but buttered noodles and Halloween candy. I probably would have had some significant health problems before I became an adult. And I'm not usually one to judge what other people eat, but the following example was egregious, and ticked off a lot of commenters in the process.