The moment your 5$ has a priority over my 2$ then you have turned Bitcoin into a Fico Score machine!
And who decides what's the "importance limit" in it?
Who decides what's "important" enough to mandate space in the blockchain?
It seems that fees should help to establish whose transaction should end up getting processed first, but if transactions are being taken outside of the built-in on chain processing systems, then I am not going to claim to know how those kinds of behaviors can be fixed.
Many of us already likely realize that there are a lot of things in the world that are not fair, so I think that it is correct to suggest that bitcoin tries to have built in incentive mechanisms that would attempt to cause it to be as fair as is feasible.. which seems to be partially based on the payment of fees to have transactions processed.
there are many ways to fix the current paradigm of transaction selection. after all bitcoin is code and code can be used to do anything
take the idea of a fee formulae
EG if someone is spending a 1confirm utxo they can be set in the formulae to need to pay 144x more then someone with a utxo that is 1 day old.
meaning spammers are penalised for spending too often.. rather than the current model where everyone is penalised because spammers fill blocks