It's the power of the princelings that kept Hu Jintao from trying to take command of the PLA. It gets worse. There are two kinds of princelings; the corrupt ones, and the reformers. The corrupt princelings really stick together, for obvious reasons. If the government gets enough evidence on a corrupt princeling, the greedy fellow can be eased out of the military. Putting corrupt princelings in jail, or executing them, is a bit much for the princeling community to handle. So the current rules are that, if you have the goods on one, you can ease him into retirement, and take back a lot of what was stolen. If nothing else, this keeps the corrupt princelings on their toes.
But then there are the reform minded princelings. These guys are not all good news. While they are down on corruption, and favor military reform, some of them have ideas the government does not approve of. Thus princelings can get away with saying that China will be quick on the trigger with its nukes in any future confrontation with the U.S., or that China will spend more money, than the government wants to, for upgrading the PLA. Not all the outspoken reformers are princelings, but they mouth off and get away with it because the reformer princelings support other reformers.
It gets still worse. These princelings have been getting stronger since the economy was loosened up 25 years ago. Like in most communist nations, the military back then owned a lot of farms and factories, as it was expected to largely take care of itself. But in a market economy, the generals found that they could turn their commercial operations into real cash cows. The military owned businesses had an edge, as the general in charge could edge out competitors by threatening force. Who's going to say no to a guy backed by tanks and artillery? This sort of thing raised a stink in the business community, and in the 1990s, the government forced the military to sell off most of its businesses. That reduced the corruption, but really made a lot of the princelings angry. This anger went back to the whole concept of a market economy, and more political freedoms. Many of the princelings are just fine with a dictatorship, run by the PLA and the Chinese Communist Party.
Many of the princelings now believe that it was a mistake to let the politicians (non-military Communist Party officials) take the country down the market economy/democracy road. Hu Jintao is apparently using his power and influence to promote princelings who back government plans, and ease into retirement, those who do not. This is risky business, although it's not believed any coalition of princelings is powerful enough, or inclined to, stage a coup. But the princelings have gotten used to doing, and saying, what they want. And this is what Hu Jintao wants to stop.
Normally, the ruler of China (as head of the Communist Party) is also the head of the armed forces. But the current ruler, Hu Jintao, did not take over command of the armed forces when he assumed control of the country in 2004. The reason for this is politics, family politics. You see, many of the senior generals come from military families. Remember that the PLA (People's Liberation Army, the official name of the Chinese armed forces) came into being nearly a century ago, in the 1920s. The early leaders, who survived until the communists took control of China in the late 1940s, found themselves suddenly wealthy and powerful. These first generation generals also had families, and sons. In classic Chinese fashion, the sons often followed in father's footsteps, and so on. There are now up to three generations of generals who trace their lineage back to the earliest days of the PLA. These second and third generation PLA generals are called the "princelings" and have become a powerful class in Chinese society.