If democracy is better than other government, why do we need to force people to choose it?

So, I was thinking, it wasn't too long ago that people were concerned with creeping communism and felt that we needed to convince wavering countries that democracy was way better. In fact, many democratic countries used various political, economic, and military means to persuade non-democratic countries to change. If democracy is so great, why do we have to shove it down people's throats?

ditto Communism

and most other -ism's for that matter