Otherwise you'd have to force the public to do things that whoever's in power sees as proper. To assume that they'd know better than everyone else is wrong.
There's 3 fundamental types of governments. Dictatorship, Democracy, or Republic. America is a republic. Although people don't know what that really means....
All of the other countries that force or convince the public to do anything besides a 'free-market' type system has either failed or the people hate their leaders because they suffer