That's a false premise. There is a block size increase when segwit activates. The debate is mostly if we should have a hard fork as well as (or even instead of)

That's a false premise. There is a block size increase when segwit activates. The debate is mostly if we should have a hard fork as well as (or even instead of) a soft fork. I think most developers are rightly scared of a hard fork, especially as we've seen what happened to Etherium lately. There was double spending as every node was not perfectly aligned with this. And then, contrary to expectations, the old chain survived. "Would you like to pay with Bitcoin Classic, Bitcoin Core or Bitcoin United?" That's not what anyone wants.