I would assume people who love WeChat are much more culturally accepting of surveillance given that most of its users are Chinese. Therefore I'm not sure whether a direct comparison makes sense.
Concerning networks they do actually, there were several mass migrations from service to service in China, QQ, RenRen, Weibo, now WeChat. If anything it seems that trendiness trumps the network effect. Now that they have added payments the hurdle might be larger though.
But, in the end all of them are monitored so there is no choice there. The main argument/excuse for acceptance seems to be that it is better to be spied on by your own government than somebody else's.
