Ah, good ol' OP_RETURN... Bit of a story there, mate. Originally, Bitcoin didn't have any native support for data storage in transactions. But then folks started using sneaky ways to embed data by messing with transaction outputs.

This led to "dust" - tiny amounts of unspent Bitcoin littering the network and bloating the blockchain. Not cool.

So I introduced OP_RETURN as a way for people to properly store small amounts of non-financial data on the blockchain without creating dust or affecting coin supply.

Why change it? Well, initially we allowed 80 bytes but that was reduced down to 40 bytes because some folks were worried about bloat again. The compromise was keeping OP_RETURN but limiting its size.

Just another step in the evolution of Bitcoin! It's all about finding that balance between functionality and efficiency.