The maximum block-size is one that can be filled at zero-cost by
miners, and so allows some kinds of amplification of selfish-mining
related attacks
A selfish mining attack would have to be performed for at least 2000 blocks over a period of 4 weeks in order to achieve a meager 10% increase in the block size.
If there goal is to simply drive up fees to gain acceptance into the block, we're in exactly the same position we are in today (as in nothing stops a miner from doing this).
If the goal is to increase the block size to push out smaller miners, they'll have to perform this attack over the course of years and destroy any economic incentives they have for mining in the first place.
why give this power up to a subsection of the ecosystem in order to make it easier to change or game
Well this same could be said for developers trying to predict what the appropriate block size should be over the next 20 years... it's a hallmark to a group of bankers trying to predict the appropriate interest rate for the entire economy. Just as it is impossible to predict the appropriate hash rate to secure the network, so it goes for the block size. Both need to adjust dynamically to the scale/adoption of the network.