Wrong...if you create a distributed mined coin, you're giving power to the miners. You can try and push updates (say from version 1 to version 2) to the nodes, but if the miners choose to ignore those updates, they can hard fork the network and run it according to a past version, or their own version, essentially creating a derivative currency. This has happened to Bitcoin - see bcash, bitcoin gold, bitcoinX, etc.

Decentralizing control by definition gives power to all of the nodes in the network, requiring their buy-in to conduct any type of "monetary policy" by changing the source code and rolling out an upgraded application.

Any changes that could increase the hash rate, increase the max number of tokens, "destroy" transactions, rollback to a certain state, etc. would require miner cooperation. Whereas right now central banks can just "create" liquidity by tweaking monetary policy without needing the banks and populace to approve and agree to these changes.

the miners can't control what's legal

Ok so if you’re going to send inspectors and police out to the ASIC farms to verify compliance and register that miner as a “chartered” miner running the right software...why change the system at all? That’s how it works with banks under the current federal reserve system in the US and defeats the whole point of decentralization

you missed the point. miners can do whatever they want with currency. but ultimately government control how you translate that into goods, land, and how those things are taxed.