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.
You're trying to setup your theme but you're experiencing errors when importing the demo content? Or you've just followed the setup guide but your website doesn't look exactly like our demo? These are common issues for which you can find easy and quick fixes.