Make it unlimited then, or grow dynamically based on historical block sizes, there's lots of options. The original limit was only added as an anti-spam measure back when anyone could mine blocks.
I would rather the core developers focus on the current capacity problems and deal with use cases like instant transactions at another time. Make bitcoin work as it's supposed to and let the community decide on adding features later - don't try to push them both together.
An unbounded block size would bring about a number of attacks. Denial of service attacks would be trivial. There's a reason Satoshi put a limit there in the first place.
I would rather the core developers focus on the current capacity problems and deal with use cases like instant transactions at another time. Make bitcoin work as it's supposed to and let the community decide on adding features later - don't try to push them both together.