The danger of centralisation of power and tyrrany of development would be to great of a cost to pay for not diverting resources. Since decentralisation implies the diversion of resources. Having multiple implementations would make the protocol more robust over the long term.
Bitcoin has multiple implementations. There also exists multiple implementations of the Bitcoin protocol, they are called altcoin. Bitcoin is absolutely voluntary and there is no such thing as "tyrany of development". If you are not satisfied with existing protocol you are welcome to either submit your own pull request, develop your own altcoin or adopt an existing one that fits your need.
You should not and can not enforce network consensus in the case of a split.
In the case of a split the two groups will each reach consensus. It's likely one group will retain the economic majority, their fork will be considered Bitcoin, the others will fork into their own altcoin.
You are advocating tyranny of the protocol, I disagree. Bitcoin is and should be voluntary.
It absolutely is. If you don't agree with the Nakamoto consensus protocol you are free to abstain yourself from using it and creating your own version.
If you think that we should all rely on the internal decision making process of Core. Then we will run into some of the same problems that large corporations and states run into, since if we wanted the Core development to reflect the will of the economic majority or possible another measure of consensus. Then we would need to attempt to construct a type of centralized governance structure on top of Bitcoin in the form of Core development, this in my opinion would be in conflict to the principles of freedom and decentralization that Bitcoin was founded upon.
Bitcoin is an engineering project. Core has attracted the best mindshare in this industry and until another development team come forward with proper credentials there is no reason we should diverge from Core's leadership.