At some point what is concise will become a subjective value. The way we make that objective is by scarce block size and the free market. Costs encourage users to be as concise as possible.
Discussion
Yes and no. The protocol is opinionated: whether to keep, alter or remove OP_RETURN, the segwit discount, and so on alter the conditions of the “free market”, i.e. the playing field that the protocol enables. Even the block size limit is opinionated. For example, with an unlimited OP_RETURN, it would be cheaper to make an inscription using it, because you wouldn’t have to split it among several transactions.
Great point. What you’re describing is a change to the protocol, which by definition would not be how it works today. But yes, removing OP_RETURN limits (which I believe is just policy anyway) and the segwit discount would make the market more free. Discriminating against data (a la current segwit discount and OP_RETURN limits does) is would not.