A key point that I think is being overlooked in the debate it the difference between developers and maintainers of the project. Developers are free to do as they please, write whatever code they want, and to submit whatever pull request they want. Maintainers are supposed to only be stewards. They should not merge code that is has mot gained general consensus among users of the codebase. If developers really really want to remove the OP_RETURN filters, they should be the ones forking bitcoin-core and pushing for its use. Only then after sufficient acceptance should it be considered for merging back into core. tl;dr bitcoin-core should not be the bleeding edge of development but should be the slower, hardened and measured approach to change.