A redesign of Bisq is coming out very soon and is currently in testing.
I am not sure if this will be addressed in the new release, but if it isn’t, you could create a feature request on GitHub using issues.
Most of the trading fee is mining fees and in general the trading fee is trying to be as low as possible, due to the open source nature of the project. It might be possible to further reduce it, but that would create some dangers of it’s own, I guess, due to getting close to the dust amount. Either way, there will be some changes coming in next few months, with the DAO and optional BSQ based fees.