I think 1MB is arbitrary, and just happens to be the status quo.

As I understand it, the people who want to keep blocksize as is want to maximise the odds of someone from a developing/under-developed country being able to eventually afford running a full node. Bitcoin is not just meant for us in developed nations, but the world.

Ironically, right now, transaction fees are such that these very people won't be able to use bitcoin. So that is a bit sad.

However, there are supposed to be scaling solutions in the works that don't require increasing the block size.

Personally, I'd rather have these scaling solutions put in place before we exclude a whole bunch of unbanked individuals just because we're impatient and want to play with our new toy.