Well, there are two different use cases. Most common, people who leave public file sharing open can get 'flashed' with unwanted files dropped onto their device. And in China and a few other countries where the governments are very control oriented, you're right, it's the government that doesn't want to allow people to communicate easily anonymously. In the first case, people tend to leave file sharing open so that they don't have to deal with setting up specific sharing credentials random people who they just met and won't see again, e.g. getting some photo's shared at a conference or party. So for them, "opening up for ten minutes" is one click, much easier than exchanging credentials, etc., so not quite as easy as leaving it open all the time, but pretty close, so it pretty much closes down the 'unwanted flashing' problem - you're only vulnerable for ten minutes, not all the time. The 'government doesn't want people to communicate anonymously easily' problem, which Apple didn't want to solve but got forced into by the Chinese government, it's good enough to make the government happy, but doesn't shut it down completely, but yeah, it's a bummer.
Still, Apple had a tough choice. When a government requires a company to do something contrary to their principles, does the company follow the laws of that country, or do they pull out the country. As far as I can recall, Apple's fought as hard as they could to stick to their principles, trying to negotiate some acceptable middle-ground, but ultimately would rather sell into a major market, even with some bonkers restrictions...