Here's an idea on why other countries haven't been too keen on adopting Western-style democracies - they read the news.
Scandals, scandals, and more scandals. The American system is almost at the civil war state right now, liberals vs. conservatives. The Canadian government has been caught in a huge money scandal, and is likely to survive it because the opposing parties are considered even more corrupt. The British government has just been revealed, through a pair of secret memos, to be George Bush's 'ho.
Does anyone really think other countries would consider these kinds of government to be an improvement?