I agree with several things you said, the flag pool and curation rewards belong on an SMT not Steem.

Yes, things change over time, but why customize STEEM to work better for curation rewards and fighting abuse if the ultimate goal is to use it as a base token?

Things change over time, but messing with inflation and curation rewards has the potential to impact business models, profits, etc. That's a pretty big risk to take on a blockchain that doesn't seem to know if it wants to be a base currency to trade SMTs on or rework the incentives to be a content discovery platform.