Hi @youfriend,
I would recommend against editing buddypress.js
by yourself for the following reasons:
1. Your changes will be erased in upcoming updates
2. Your changes might lead to conflict with Cera, BuddyPress and Grimlock for BuddyPress features.
We can leave this request open and implement it in the future, when we have less on our plate. I agree with you, if you have a very active post in your activity stream, it can be quickly cluttered with long comment threads.