It seems to me than accepting USD as payment is accepting a wasting asset. And accepting BTC is accepting a generational asset. (Which, if the business were to hodl, cash flow problems would arise.)
But how would business owners account for inflation, future value, etc? Is current exchange rate the only way? I suppose we do that with other currencies every day.
I'm inclined to offer customers a discount for BTC to account for the longer-term sacrifice they're making and zero processing fees and better privacy, etc.