Transaction volume itself leads to centralization too, simply by ensuring that only a miner able to keep up with the large volume of low-fee transactions can make a profit.
I really don't understand this logic.
Yes, it is a fact of life that if you have a system where people are competing, the people who are less efficient will be driven out of business. So there will be fewer people in that business.
You seem to be saying that we should subsidize inefficient miners by limiting the block size, therefore driving up fees and making users pay for their inefficiency.
All in the name of vague worries about "too much centralization."