I'm not sure, if I missed something, but why isn't block size limit defined dynamically based on previous usage (plus some safety margin)?
Powerful entities would game the system, turning it into a proof-of-bandwidth system, which would be a bad thing.
They can only do this as long as network bandwidth is donated and the consumers of it do not pay the suppliers.
Fix that problem and we'll never need to have this debate again.
It doesn't need to be fixed, it needs to be offered by suppliers. If there is a demand, they will supply it. They are not supplying it because vendors and consumers are not aware of the issue. Education is what's needed. If they can be shown the profitability, then they will fill the niche.