Because gas is like the cost of the paper. I wouldn't want my bank selling a fancier cheque just to charge more, but I do expect to cover the costs of the necessary anti-fraud features, etc. Similar to the cost of the code to verify the transaction.
But yes, it should be lower where possible. Both by code optimization and blockchain/architecture choices.
When my bank says they're sending me a new checkbook for free, I definitely do not expect to pay the price of the paper or anti-fraud features. Do you?
Network fees for blockchain are the equivalence of taxes. People aren't okay with taxes, but they're the price you need to pay to participate in the financial system.
But yes, it should be lower where possible. Both by code optimization and blockchain/architecture choices.