The fee is effectively burned in all the proposed forms of the operation.

While it "might" make sense to add 5% to the normal conversion (HBD -> Hive), it would require more work/testing, and I don't think there's a pressing need for it. And HBD -> Hive conversion is kind of critical to holding of HBD, because traditionally exchanges have had much less liquidity for HBD than for Hive (hopefully we can change that, of course).