[prolixus]

I think your last paragraph is right.

Right now there's a default transaction inclusion policy in Bitcoin Core that only includes a small number of low to zero fee transactions. Under current conditions zero fee transactions have to wait a while to be confirmed.

There's no proposal to change the default allowance for below standard fee transactions if the block size increases, so assuming cheap means zero or very low fee the increase in size will come from standard fee transactions which means increasing capacity won't drive down existing fees.