the max block space can be reduced with a soft fork
That would drive up L1 fees from scarcity, not from adding more value. That's the equivalent of raising prices of a good, without providing more value.
My entire post is to suggest that finding a way to add more value, to compliment what a user gets from the "fees", is economically more sustainable than any other approach.
If a proposal ever landed to reduce block size, I imagine there would be an entire faction of people beating the drum of the message behind my post. The community would be divided, I'm sure.