• This is most likely related to viewing Dropbox as a source of information sharing that cannot be controlled. It is a testament to Dropbox's influence, that the government would see DB as a threat. Until DB can promise the government a sufficient amount of control over the content shared, they won't be allowed to be accessed here. (See Google)
• Up until this point, the whole Google fiasco has been settled quite well.
1. Google didn't want to remain in China and be forced to censor content. Check.
2. China didn't want to make an exception. Check.
3. Google still has a presence in China and doesn't have to filter its content. China hasn't lost face and been forced to make an exception. Check.
Even though it's not ideal and the service gets blocked sometimes, I sense that China and Google came to an agreement together that Google's move to Hong Kong would be the most appropriate thing to accomplish the two seemingly contradictory goals. You will note that if China didn't want Google at all, they would've blocked Google in HK from day one. That's not to say that Google will never be blocked, but at this point it's safe to say that the government does not see Google as a big enough threat to warrant being blocked.
• Could DB do something similar? Maybe. It seems that DB would have to reach out to the Chinese government and cooperate to some degree in a sign to show that there is a desire to be in China. Then, like Google, they could choose to pull out to HK, where hopefully there would continue to be this unspoken agreement to let foreign companies be. This might backfire in that the government might just pull the plug on all foreign companies in HK, feeling that the initial overtures were superficial and that there was just a desire to be given a certain level of access in China without having to abide by the other stipulations that other companies have. If DB chose to try and cooperate with the government, this would lead to some form of censorship (either by DB, the government, or by the users themselves) thus defeating some of the benefit of using DB. DB is fundamentally different from the service that Google offers, though, so following Google's path might not work.
• This whole thing makes me sad. Chinese culture is fundamentally different from Western culture. That doesn't justify certain things but you'll have to talk to people (real people…not just read chinaSMACK) to understand better some of the reasons for these policies. The point is, though, that the Chinese government is dealing with a different set of problems with a different set of values than other Western governments. Until there are some changes in the problems or in the values, we'll continue to see different permutations of these kinds of policies. I've also seen a pattern of non-risk taking behavior here. Policies like these discourage people take chances at producing great ideas. Most Chinese comp sci students want to get a good job at a stable company. From what I have seen, and I'm still learning a lot about tech here, the lack of the entrepreneurial spirit is related to a lack in the quality of programming. There isn't the same kind of cut-throat competition that I've seen in the States and this leads to less motivation for learning the best (or better) way to do things. There are obvious exceptions to this, but in general, the motivation for someone to set up their own business is very low. It's too risky.