People talk as if there is a Bitcoin conspiracy where some central entity decides all things Bitcoin-- where blockstream is the equivalent of the illuminati. If someone thinks they can do a better job then go fork the source and convince everyone else why it's better.
Consensus aside, this is a lot harder said than done. one of the reasons btcd is not widely adopted, even though it's purporting to be 100% compliant with core, is that there is no formal definition of what that even means. to be 100% compatible with the bitcoin protocol is to be 100% compatible with core - bugs and all. the community needs an RFC like paper describing in details what 100% compatible means. Then we can safely run other nodes without worrying that we'll get screwed by not having the same bug as core for example.
I'm not one to believe in conspiracies or even subscribe to the thinking of core==blockstream. But I don't think you'll disagree that what goes into the consensus protocol is under control of the 5 maintainers
The consensus protocol is dictated by exactly that, consensus, not this allegedly omnipotent cabal.
Miners are a different story though; understandably, they're very reluctant to change (who would with so much money on the line). It is also unfortunate how miners switch back and forth between classic and core so quickly.