The problem Bitcoin is facing is not so much the technical question of what blocksize would be best. It's a war about who is in the drivers seat. The current developers of Core want to turn Bitcoin into what they call a "settlement layer" and end its original function as a payment system. Then they want to build new services on top of this "settlement layer". Most (all?) of them are organized in a company called "Blockstream" that received $73 millions in funding to build these new layers. This turns away the original crowd of hackers who liked Bitcoin in the early days. The hackers and users want to keep the original vision of a "Peer-to-Peer Electronic Cash System" as outlined in the original Bitcoin Paper:
https://bitcoin.org/bitcoin.pdf
Also check the discussion about this on reddit:
https://www.reddit.com/r/technology/comments/48zggz/a_behind...