Of course, there are many reasons why many different people hate the mullahs. The upper class in Iran, for example, still resent the fact that they've lost a country that they used to rule, and are now ruled by, as they see it, low class, uneducated fundamentalists.
There is one adverse effect that for me stood out from all the other changes the Mullahs had. It seems to have caused the disenchantment of a lot of the population with Islam.
Let me explain. In Bahrain, for example, you find a lot of people who are not particularly practicing muslems. They drink, don't pray, and some might even gamble or smoke weed. However, if you ask the majority of these people, "Are you muslim?", most of them would reply that they are muslims, but are not practicing. Most of them would probably also believe in the quran and that Mohammed (pbuh) was a prophet.
In Iran, however, I was surprised by the amount of people that openly scorn Islam. To make a comparison, if you ask someone who is not a practicing muslim there if he is a muslim, he'd tell you no I'm not a muslim. A surprising amount of people openly say that they do not believe in Islam as a religion, and some don't even recognize Mohammed (pbuh) as a prophet. Some even openly make fun of some of their Shi3a sect of 12th imams beliefs.
My conjecture is that the way Mullahs have warped the country, and because of the Mullah's corruption and other bad deeds, people have started associating Islam with the Mullahs, and some people, unfortunately, have started seeing Islam as being just as bankrupt as the Mullahs. For example, I was once sitting with a bunch of people in the lobby of the Sheraton Hotel (of course this was its name before the revolution), and above us on a sign it was writtten, "Islam is the highest form of civilization. One of the girls with us read that out with a snicker and a dose of irony. I asked her, "so you don't believe Islamic civilization is one of the most developed in the world?" She pointed at her hejab and replied, " Is this in any way civilization?" I replied, " But the main point of Islam is not about the Hejab. It's about equality, respect,restraint. It also advocates social cooperation, ......." Her reply was , " Save your lecture for yourself. We have the Mullahs here who repeat your same words and more, and all we've seen from them is chaos and backwardness."
I did not know how to reply back.
One final point I would like to make. From my (very limited) general reading of Islamic History as it developed over the ages, one of the most defining thing to me has been its leniency and acceptance of people of all sects, races, and faiths. Even back in the eightth century and beyond, all that Islamic ruler imposed on non-Islamic followers was to pay a small "jezyeh" or amount of money to live in an Islamic country, and then they were left to conduct their life as they saw fit. This, compared to the other empires and civilizations developed at that time, was extremely lenient, especially when compared with the persecution and killing a lot of them carried out. In fact, the earliest Islamic rulers did not even actively encourage people to convert to Islam (as they saw in this an increase in the number of people sharing power, since most of the people they ruled were not muslims). People themselves (for whatever reason, being that they were impressed by Islam, or because they saw in conversion societal and economic advantages) converted. Where has this tolerance and leniency been lost in our modern age? Why is it that most Islamic countries try to impose certain customs and laws on people who live in it? If we are so keen on emulating earlier Islamic rule, why don't we follow them in a general principle of tolerance?
My experience, from Iran and other places, seems to show that the more a ruler tries to impose a certain idea on his dominions, until he reaches the point of openly coercing them, the more his subjects rebel. The more a ruler tries to slowly teach his follwers certain ideas, and the more he shows the advantages of such thinking without coercion, the more successful he is. For example, in Bahrain, where certain Islamic schools (e.g. salafi and wahabbi) spread their thinking through charity and clever preaching, they have been relatively successful, especially when compared to Iran, where some people have reached the stage of openly rejecting Islam due to the Mullahs' coercion.
Maybe we can learn from this in Bahrain, and see that forcing people to live under a "promotion of virtue and prevention of vice" squad, or coercing people into single-sex universities, might backfire and make people rebel even more against the more fundamental, and more important ideas of Islam, such as people's equality, the importance of the family, civil rule, and (which for me is one of the most important, if not the most important quality; maybe I'll write a blog on it)progress.