Not necessarily. There is a certain theshhold where there is effective pressure without meaningfully incentivizing the robust development of direct miner submission. Where that threshold is and where it will be in the future, I don't know, nor do I know how to keep miners' decisions in line with economic noderunners.

This is very much key to the issue, keeping robust choice in storage and mempool policy to enable spam to be kept out, while also keeping miners interested in mining blocks reflective of the choices of nodes that care about the Bitcoin ethos.

I think individual choices as regards spam filters and the configurable pricing for OP_RETURN that Knots offers is likely, though not certainly, a very good approach that puts pressure against spam while allowing individual choice AND preventing miners from bypassing the nodes in mass. There might be better solutions.