Iraq and Democracy

This will be my last post on this subject.
I had a look around at some bits of research to try to understand why some countries become democratic and others don't. It's often spoke about in terms of people becoming rich enough, but we can look at countries like Qatar that aren't democratic that have a very high GDP per capita and it doesn't quite add up.
I stumbled across a paper on  The Impact of Economic Development on Democracy by Evelyne Huber, Dietrich Rueschemeyer, and John D. Stephens which contained the following:-

Our central thesis, and indeed our most basic finding, can now be stated in stark fashion: Capitalist development is related to democracy because it shifts the balance of class power, because it weakens the power of the landlord class and strengthens subordinate classes. The working and the middle classes—unlike other subordinate classes in history—gain an unprecedented capacity for self-organization due to such developments as urbanization, factory production, and new forms of communication and transportation.
If we look at Western democracies that's pretty much the case. Countries like Taiwan and South Korea also became democracies after their countries industrialised.
If you look at countries like Qatar or Iraq, though, while they're advanced countries, the shift in the balance of class power hasn't happened in the same way. The wealth of the country is still under the control of the leaders, that wealth being the oil in the ground (nearly half of Iraqi GDP is oil). On the other hand, Egypt, a country that is developing and moving away from a dependence on oil and tourism does seem to be rising up on their own. Early days perhaps, but they seem to fit the pattern.
The one place we successfully imposed democracy was Japan which was already quite an advanced industrialized economy in 1945.
Which now makes me ponder if imposing democracy, shortcutting the process and not building up the structures is sustainable. Can you intervene and create it and expect it to last, or does the lack of class shift mean that it's a house built on sand?