Relay policy does and has sufficed since inception. That’s why 99% of op_returns are under the 83 byte default relay limit, and so no consensus change was necessary.
Now the reference implementation has uncapped those limits, meaning that version of node software now supports the relaying of large continuous chunks of arbitrary data by default. We can expect to see more large op_returns being mined because of the changes in core 30, and so a consensus change may be necessary if we do not want bitcoin to become an arbitrary file storage system…
