I found this conversation really helpful. Paul explains it for the non-technical folks.

https://www.whatbitcoindid.com/podcast/should-drivechains-come-to-bitcoin

The other thing I like about it is that it can be tried without impacting users who have no interest in it. If you just want to use Bitcoin mainchain as is, it doesn't affect you. But there seems to be a lot of upside in terms of useful projects (zcash but on bitcoin, for example) and more txn fees for miners which will be more important as the block reward decreases.