The collapse of the Russian Empire has multiple reasons.

Indeed Nicholas II is often seen as a "quiet housefather", which is not a good trait for a Tsar to have. He wasn't very interested in politics and almost always followed his advisors or let others, like his prime minister Piotr Stolypin due all the governing for him. Though, his character was not the underlying cause for the revolution. It was only a very minor factor.

The most basic underlying cause of the collapse is probably the problem of the serfs. While Western Europe got rid of serfdom early on in the early modern period, Russia abolished serfdom officially in 1861. Unlike Western European monarchs, who based their power on the cities, the Russian Tsars based their power on the nobility. The nobility lived of the production of their landholdings, but the land had to be worked. Therefore people were tied to the villages (which were owned by the nobles). That means they were forbidden to leave the village and were obliged to work the lands of their lord. This supplied the nobles with very, very cheap labour.

But Alexander II (ruled 1855-1881) realized this situation could not be held forever. There were multiple reasons:

1. There was a need for a better and larger Russian army (the Russian army lost the Crimean War). Therefore Alexander wanted to abolish serfdom, and create a healthier generation of youths for the army.
2. As the population was growing, there were more and more serfs. The elite feared the 'revolution', which had already taken place in France about 60 years earlier and in other parts of Western Europe. They believed that if the people had better lives, they would not revolt.
3. Russia needed to industrialize to keep up with Western Europe (~Industrial Revolution). But since the serfs were tied to the land, they could not leave their villages to move to the cities and work in the factories. Abolishing serfdom would provide a gigantic amount of labour for the factories.
4. There was a growing moral resentment, just like there was a discussion in the United States on if slavery was morally right.

Then, in 1861, Alexander II issued the Emancipation Manifesto which set all of the serfs free. But, there was a major but:

The nobles owned the land, so if the serfs would be set free, they would own nothing. That would only lead to major crime waves and chaos (and possibly make the serfs revolutionaries, whom they feared). Therefore Alexander decided that the land would belong to the people who farmed it. Though, that would make the nobles (on whom the Tsar based his power) unhappy. So he had to compensate them. He basically bought all of the land of the nobles, but couldn't afford that enormous price. Therefore the (former) serfs would have to repay him. That lead to other problems:

1. The state did not know all of its subjects. Therefore it assigned the Mirs (= village councils) as being responsible for repaying the debt to the Tsar. The Mirs however, forbid (forbade?) the villagers of leaving the village, because if they all left, nobody could pay the debt. So the villagers were still tied to the land + they had to pay to the Mir (who now basically took the role of the nobles). Eventhough they were now officially 'emancipated', they still were de facto serfs.
2. Nobles were rich and could make big investments in their lands to increase its production. Simple single farmers however, were not and could not make these investments. Meanwhile, farmers in the Americas cultivated gigantic plots of lands and used modern machinery. Consequence: America flooded Europe with cheap agricultural products. The farmers could not withstand that concurrention and could not sell their production. That resulted in them being unable to repay the debts to the Tsar, so the 'loans' (=debts) were constantly extended. It seemed as if the debt would never be repayed and they would never be really free. All the while the people kept getting poorer due to the concurrention with America. (The cheap food from America did not only affect Russia. Western European farmers were also affected. This caused a massive migration from Europe to the New World in the 19th century.)
3. When the Emancipation Manifesto was decreed, all of the former serfs were assigned a plot of land. Though, afterwards the population only grew, which resulted in the people only having smaller plots of land (and thus even smaller income) due to dividing the land between several heirs when the original owner died, or younger children getting nothing at all.

The people were not free and were only getting poorer. This would make them very influencable by radical ideologists, like the communists who promised a better world.

So basically the whole serfdom problem is the underlying reason for the collapse of the tsaristic regime. It did not necessairly have to result in a communist state, though. The bolsjevists gained most of their supporters among factory workers and soldiers. Peasants would mostly support other groups (Liberals, Social Revolutionaries,...). All of these groups cooperated during the February Revolution (which was also fuelled by the discontent over World War 1), which overthrew the tsarist regime. At that point the monarchy was lost, but Russia could have evolved along different paths.

A provisional government was formed with members from all sorts of political groups. But there were also the 'Sovjets', soldier and worker federations (a little bit like unions, but not entirely). These Sovjets were controlled by the Bolsjevists. It is with the October Revolution, when the Sovjets stormed and abolished the provisional government, that the starting sign for the later USSR has been given. But even then they have defeat all kinds of other groups and movements (commonly referred to as 'the Whites') during the Russian Civil War.

But, as I said: things could have gone entirely different even after the monarchy collapsed. One can only imagine how Russia would have looked if the Sovjets failed to overthrow the provisional government.

It's a complicated matter, but I've tried to explain it as clearly as I could. I hope this helped. :-)

Source: I got most of this information from a course I took on the history of Russia and the Soviet Union. That course on its turn, was mostly based on "A Concise History of Russia" by Paul Bushkovitch.