This is simply untrue. Lets imagine that 75% of miners start paying themselves 50 BTC again instead of 25 BTC per block. Nothing, it's the same as if they simply turned off (which they may do when the subsidy halves). Nodes simply ignore their blocks. So much for "direct control". Miners do have power over some things-- they can choose the order of unconfirmed and recently confirmed transactions; but they can't break the rules of the system enforced by the nodes... if they do, they're not miners anymore as far as the nodes are concerned.
Of course nodes could ignore their blocks, and holders can dump their coins. If a particular change is disagreeable enough to a sufficient portion of the market... an opportunity exists to change the proof of work and lower the difficulty to continue on an altchain that could possibly become more popular than the original. In any case, a blockchain needs solved blocks, and solved blocks require PoW.
It baffles me how you could remain so interested in Bitcoin if you see its central free market based consensus mechanism as natively flawed and irrelevant. Again, created sick, and commanded to be well.
Miners are incentivized by the market to make decisions, they don't make these decisions in a vacuum, free of consequence.