I’m not OP, but I think that immediately suggests a benefit? Like if your Mini Program has 10 features, one of them uses Discourse, and going to a browser for just that is distracting for a user (especially if they’ll need to go back to Mini Program later).
However if I were OP I would think consider it not worth the effort, especially since in addition to login with WeChat (I’d wager a guess that’s the only way to obtain user openid), the user also has to provide an email, which may look suspicious and therefore reduce its audience.
(Along with other complications, like if user decides not to use the WeChat login, should they bypass WeChat audit, and if not, how to get an openid from them. The fundemental solution seems to be to lock your forum to WeChat login only and let non-WeChat users have fun figuring out how to get a WeChat account 
)