I suppose we can give feedback to Airbnb on this by calling into customer service and explaining the problems this feature has for you. What I think is that it would be best if Airbnb allowed hosts to set weekly or monthly prices EITHER way, either as fixed rates, or as discounts. I find it frustrating that whenever someone inquires and asks what my monthly rate is, now because it is a % and not a fixed amount, I can't see it right away on my pricing sheet, I have to get out a calculator and calculate it every single time now. I prefer being able to set a fixed amount for the weekly or monthly rate.
I do see the advantage of having these rates also shown as a discount amount, because it clarifies to the guest that they ARE getting a discount for weekly or monthly stays. This may help cut down on the number of guests who want to stay for over a week, and ask "can I have a discount?" not realizing that they ALREADY are getting a discount -- ditto for those wanting to stay a month or more. However, I dont' see why we can't just set a fixed rate, say for instance $1500 a month, and then have a note automatically appear next to that, indicating the % discount that amount represents over the nightly rate eg: "$1500/month (25% discount over nightly rate)." I think presenting it that way would be ideal for all concerned.