If you're willing to listen to an American's perspective on why Star Wars (especially this one) is so loved:
Star Wars was the first great movie that was aimed towards a demographic of teens and adults, especially males. It spawned a trilogy of movies, which was extremely well-received, and was arguably the first to do so without a huge drop-off of quality (Godfather). The movie spawned a LOT of other things off - novels, video games (KOTOR is arguably one of the best ever made), as well as a massive toy/merchandise empire of which no movie has ever rivaled. TFA alone will bring in $5 billion in toy/merchandising rights, which dwarfs the box office run it has.
You then take the story that ended in 1984, and announce that its coming back with all of the old major characters.. The original actors, the original puppets, everything. Finally, it releases and is arguably as good as most people wanted in a series that was a continuation of the original (whereas the Prequels were an unfathomable letdown).. That is why its so well received. Its a cultural phenomenon that is hard to explain if you didn't grow up around the franchise for the past 4 decades.
One day, China will have its own great unique movie series and universe that one could equivocate it to in terms of size and scope of its notoriety, but there are very few in movie history that one can compare it to, so its hard to "Get" when you're being plunged into the series, as opposed to watching the movies dozens of times growing up, and having to live through what were bad prequels (which if you look at IMDB ratings, you can see they were very disliked, whereas the consensus is that TFA towers above them, although is not as good as ANH or ESB).
In the end, a lot of people in the west that had access to movies grew up with the series since the 1970s... This is also why its doing well in Japan, since the movies were featured prominently over there as well ($60m and likely to surpass $100m in a market that has been down for years).
Hopefully that explains it as best as possible.