Antoine's post is quite interesting too (responding to Mechanic asking why increasing OP_return would be useful).

You know why, you're just engaging in bad faith. But i'll repeat the reason for anyone lurking who's not aware.

The point of making it bigger was that some applications want to have a proof of publication for a modicum amount of data (like Lightning does) in case a specific transaction in an offchain protocol is broadcast.

This data needs to be in the non-witness part of the transaction, so they can't use the (cheaper and already-available) inscription mechanism. They also cannot use OP_RETURN outputs because of the misguided 80-byte policy limit on those.

If they only wanted to store data onchain, they wouldn't be too concerned about policy limits. They could just have leveraged private APIs to miners (as they unfortunately already do for other transactions in their protocol), or even just used Libre Relay.

But what they are really interested in isn't to store this small amount of data, is to do so while using the p2p transaction relay network. This is why the policy limits were a binding constraint for them, and are not one for people who just want to store arbitrary data onchain regardless of how it gets there. The reason why they want to use the p2p transaction relay network is because their transactions are time-dependant (again, like in Lightning) and the p2p transaction relay network is the best mechanism available today to propagate your transaction to as many miners as possible in a timely manner, while making it hard for an adversary to prevent its propagation.

Because they wouldn't give up this property, important to the security of their protocol, they routed around the OP_RETURN policy limit by storing the data in unspendable outputs instead. This method is strictly more harmful to everybody, and it was incentivized by the misguided policy limits on OP_RETURN outputs (which don't achieve anything anymore since inscriptions and since people have started being serious about bypassing mempool policy).

Because the policy limit on OP_RETURN outputs was not achieving anything but incentivizing harmful behaviour, Bitcoin Core contributors decided collectively after long discussions to get rid of it.