I think this is a fantastic idea. If they gave an additional incentive like an extra 1-2% APR on a more long term lock period for the HBD savings, we could get additional demand for HBD, which would keep the HBD peg better at exchanges, would cause more HIVE>HBD conversions thus reducing HIVE supply and increasing price, and the increasing amount of locked HBD for long periods would keep a constant need to mint new HBD and keep the demand cycle flowing and compound the positive effects.

I think this is what we are missing here honestly. Haven Protocol also needs something like this for their Mint & Burn system too, perhaps I will look into how to submit a proposal over there.

And BTW, while I am not sure how optimal the exact percentages are, I do think the Haircut Rule is overall a very good policy for the ecosystem.