Why can’t tx fees be determined from a % of the amount of ETH being transacted, regardless of the USD price of ETH?
For example, if I am sending 1 ETH and if the tx fee is 0.001% then the fee would be 0.00001 ETH. And if I am sending 1000 ETH, then the fee would be 0.01 ETH. Not only is this technically logical, it is also impartial to fiat value as the sender will only incur 0.001% fee for whatever the amount being transacted in whatever denomination he chooses, thus practically fair.
And that % can be determined from factors like your memory storage space example and this adjusts automatically on its own to future expansion and contraction, for example a sudden increase of storage space or sudden reduction of the same for whatever the reason be it due to nano tech or nuclear fallout.