Though I could also point out that the original decision was 32MB per block, not 1MB or 4MB.
Yes, but 1 MB is what most of the nodes accepted. It is mainly about backward-compatibility.
...
No, it is simply that core is completely against it, they prefer to use the fake excuse of never doing a hard fork.
Heck I've asked such questions of them back in 2011 - and got nowhere with it.
e.g. one of a number I've done:
https://bitcointalk.org/index.php?topic=51504.0When core wanted to force miners to use Segwit, there was also BIP100 that got greater than 70% block coinbase approval with the mining community.
Alas core didn't want it and that was the end of it.