France wanted their independence back during the German occupation of France (1940-1944), the Chinese wanted their independence back during the Japanese occupation of China (1937-1944), and Tibet have wanted their independence back since 1950.
Note that the West trades heavily with China, not Tibet, and as a result have actually been remarkably tolerant. South Africa was banned from the Olympic Games for 30 years, and subject to various sanctions, due to their policy of apartheid.
Since 1950, there have been 400,000 deaths in Tibet, 90,000 have fled the region and those who remain have been subject to what has variously been described as apartheid or 'cultural genocide'.
It is true that Tibet has historically been a part of China, but Poland has historically been part of Germany, yet few would condone Hitler's later invasion of Poland. More relevant is the fact that Tibet enjoyed de facto independence from 1913 to 1950. Although history, per se, is not important, what really matters is the future and human nature (which is unchanging). Evolved in-group/out-group biases cause men to have a strong sense of identity with men of their own culture/ethnicity, and tend to act so as to exclude others. Tibetans, historically of northern Chinese origin, are a homogenous group from the point of view of linguistics and religion and are genetically closer to the people of Japan, Korea and Bhutan than their Chinese neighbours. Tibetans might prefer to be ruled by other Tibetans rather than by Chinese.
Tibet boasts a rich culture, religion is extremely important to the Tibetans and they have their own language, all of which are being destroyed. It is not necessary to romanticize the former feudal regime to denounce the Chinese occupation. It is true that the Tibetans were a backward culture, but the West now recognize that even primitive tribes in the Amazon or New Guinea deserve to be left alone, with their culture intact. Nor can China blame the Dalai Lama, the recent unrest erupted in spite of his frequent calls for restraint. Tibet is full of ethnic conflict and rich in mineral resources, another Iraq without even the pretence of a democracy. I hope the Chinese government watched the Olympic protests (thanks to censorship and the government's control of the media, the rest of China can not) and take note, otherwise Tibet is doomed.