The main justification from Core for the OP_RETURN uncap is “harm reduction”.

The argument is that inscriptions done via the segwit/taproot hack have potential to do more damage than inscriptions via OP_RETURN.

Thing is, LukeDashjr made a PR in 2023 to fix the vulnerability introduced by taproot.

PR #28408

It would “effectively limit arbitrary data carried via newer methods (including SegWit witness data and Taproot scripts), which inscriptions/Ordinals were using to bypass the existing OP_RETURN-based limits and embed larger payloads.”

If that had been merged, the current harm reduction narrative wouldn’t even be there.

It wasn’t merged. Core didn’t want it.

Peter Todd was among those who Nacked it with this rationale:

“The transactions targeted by this pull-req are a very significant source of fee revenue for miners. It is very unlikely that minres will give up that source of revenue. Censoring those transactions would simply encourage the development of private mempools - harmful to small miners - while making fee estimation less reliable.”

Note the use of the word “censoring” to describe fixing a very recently introduced vulnerability that opened up for ordinals.

Self inflicted wound, willingly not patched up, used as rationale for a new self inflicted wound.