Miners are the arbiters of consensus because they extend the blockchain. They are the group who's interests are most closely aligned with the success of bitcoin. They are the only people with a commitment. Hodlers can dump whenever they lose faith. Miners have to fight to preserve their investment. If they do not do what is best for bitcoin, they lose BIG. Who do you want in charge, fickle hodlers who can jump ship to a different coin if they screw this one up, or miners who have huge amounts of capital invested in hardware that is useless without bitcoin? Every governance system in the world is minority rule. Pure democracy is 2 wolves and a sheep deciding what to have for dinner and nobody is dumb enough to use it as a governance model for anything of value. It would be even dumber to cast votes based on who has the most money.
Miners are the arbiters, but they are not the government. Heck, I don't even think
the arbiters fits here. They have kinda limited decision scope: they decide on which chain, among valid ones, to build upon. They also decide which transactions to include in their blocks. This results in a side effect of them being able to do things like blacklisting transactions. This ability I'd like to strip them down of. Governance is a much wider term, and for better or for worse, there seem to be no such working thing in Bitcoin.