Nobody bashes Nintendo, Sony or Microsoft for only allowing licensed games on their consoles.
Fact is that this sort of control can improve the user experience.
I own an iPad 2 and I certainly see the downsides of Apples approach, but the upside are tons of quality apps, piece of mind and a great user experience.
This is not about freedom of choice or about the "very basic concept of democracy" (are u serious?), it's about choosing the device that best fits your needs.
This would be a different story if Apple had a monopoly on smartphones or tablets, but that's not the case.
btw: If Apple ever started to "wall in" Macintosh OS, they'd be dead to me. But phones and tablets are a completely different thing.