as far as I can say it's because of several facts including A & B as you've indicated, as well as some other issues. maybe I'm wrong but besides the similarities, the situation is different in these countries.
in Saudi, there is a regime like you described in A. that certainly is a sign of lack of democracy. but other than that, the question is, do the Saudis (the ordinary people not the fat rich Sheiks) want to gain freedom/democracy? I watch some of their TV channels. their current leaders are all western followers in almost everything, and therefore they might like to have a shell of democracy (not the core concept, as they find it dangerous), for example allowing women to drive cars, to vote; or cinemas etc. but they can't. the reason is, Saudis themselves resist. their beliefs of Islam is the radical version which makes the portray of Islam in west. with few exceptions they don't like to change. some indicate it's because of the geographical attitudes since they've lived in deserts and some relate it to Islam source etc. anyway, generally they don't want changes resulting in democracy, or it's less than the two other countries discussed here.
on the other hand the key factor to change, elite and public understanding of politics also are missed. here in Y!A I have some Saudi friends. they know English, they are educated and we can say they're of the best ones of their society; none of them involves in political questions or at least the questions insulting their culture and beliefs (the stupid questions that could come to the mind of some brainwashed westerners). when the public understanding in political issues is not strong, it'll be hard to raise elite.
therefore although the fat cats in Saudi like to show their regime democratic, it will take much longer for them to gain it (which I think we can bet on centuries).
in Iraq, people are not like Saudis. again we might consider it due to the big geographical differences with Saudi. people seek changes and would gain it, but the dictatorship of Saddam, the war with Iran, plus the oil as you mentioned prevented it; the wrong way of US and some western governments in spreading democracy. their democracy recipe makes it worse, maybe because it's imperialistic. they will make changes I guess it will not take long to see that in Iraq.
in Iran, I think the situation is better. Iran has a historical culture, it has been a big empire for centuries, and many different regimes have been experienced. Iranians themselves are much more interested in politics and changes; puppet regimes cannot be tolerated by them -tried once- since they want to participate in leadership. I believe this is the important reason to expect democracy presence in Iran.
as an example, consider the debates and unrest about the recent election in Iran. I don't want to say who was right or wrong, but important is, people themselves participate in discussions, and the strong will to change someday would work. Iran is on its own way to gain democracy.
many of Arab regimes dislike Iran; they always fear their people would see Iranians and would try do what they do. they prefer Israel compared to Iran; the main reason is, Israel is an enemy to Islam, everyone knows it, but Iran is not an enemy. a Muslim state with independent active diplomacy which Arabs, the nations, like and might want to implement it in their own countries. as an example, in Egypt, Saudi and Syria the elite and people have tried to make a copy of current events of Iran (the election) in their own country. this is the big issue of Arabs with Iran. their nations like to gain what Iranians are trying to gain, but their Sheiks dislike. Ahmadinejad is more popular in neighborhood than his own country. many Arabs worship him for his courage and stance against the imperialism. it cannot be compared to average Arab governors, corrupt & rich puppets.
I might be wrong but based on what I see in Y!A, Iranians know more about politics compared to neighborhood and even Americans. it's a good reason to think no matter what regime it has, Iran will gain democracy, while they stand against imperialism.