Because the block limit is not creating a fees market. The block reward is too high and masks the theoretical "bidding" process for block space
You are right there is no fees market yet, but not for the reason you state.
The block limit is not currently creating a market because it is not yet tight and bigger blocks will not be tight for yet more time.
Miners' only freedom is the freedom to exclude transactions. Can it be used to press users to pay higher fees?
Only if either
1) the space is scarce
2) supported by a rational lower limit to fee, no sane miner crosses
3) played in cartel
You want to eliminate 1) hoping that 2) holds so we do not fall through to 3)
Gaving quantified a rational lower limit to transaction fee as 0.0032/KB. A miner that includes a transaction paying less is no longer compensated for his increased orhpan cost. Miners currently accept even less, that tells miner are either dumb or the rational limit is lower. I suspect people deploying hundreds of millions in equipment would not act dumb for a prolonged time period.