You raised some good points here, and some not so good points here, so I would like to address some of them:

Steem is not and never has been "proof of brain" but more proof of stake.

I can agree with this to an extent. I would personally say it's more of a hybrid, since it's still individuals deciding what they're supporting, and those decisions are weighted by how much skin they have in the game, but I can see the argument both ways.

Then comes free downvotes, which is a terribly stupid idea. Now every account has more power to do harm than it has to do good. In the past people had to ask themselves if it was worth it to them to take a hit in order to be a dick to someone, but no, now the dickslaps are free. We just made it so accounts can put more negativity into the environment than they can positivity, great plan...

With 10 free upvotes and 2 free downvotes a day, I would say each account has 5X the capacity to positively affect someone's rewards than negatively affect them. From my perspective, this has worked better than predicted. Bid bots are scrambling to react to the new market, the trending page is looking much more usable, and Steem's biggest reward pool abusers are finally getting their posts drained. Has it been perfect? Absolutely not. Is it better than it was? I can say without a doubt that's it's much better since now we don't have to ask our biggest stakeholders to choose between losing curation rewards or fighting abuse.

I have been running a flag neutralization service, named @freezepeach, every single day for over 2 years now. I did it because I hated seeing people being driven off the platform for having the "wrong" opinion, and I wanted to do something about it. Flag abuse is real, and it hurts steem, but we need flags or else the shared reward pool becomes exploited in a classic case of the tragedy of the commons.

The value of Steem, as I see it, is the immutable blogging space available to a person online. I think the more logical path for its design is to give SP a cap on all accounts, and that SP is not reclaimable. This means that for an account to have SP you are effectively burning that STEEM, or at least making something fungible into a non-fungible asset.

I don't know how I feel about a cap on steem power, that doesn't seem logical to me but I'd have to think about it more. The never powering down option is interesting though, and definitely needs more exploring. That would radically change things, but I'm not sure in what ways exactly. The devil is always in the details.

That way no single account could be 1000x the vote influence of another account, and owning STEEM would be more about owning decentralized "digital blog property" rather than some currency. The currency could be like potential parcels, very much similar to Mana/Land with the Decentraland project on Ethereum.

What's inherently wrong about having 1000x more influence? What about 999X the influence? 500X? 100X? What makes any of those other figures better or worse? If you own any amount of Steem above 50 SP, then essentially you have a working blog and have "digital blog property" as you put it. It's the influence that comes with putting your money where your mouth is, and that's important in structuring things like resources, rewards, and future forks of the platform.

(paraphrased) Why not fork Steem? Why SMTs? Steem accounts are a barrier to entry.

Plenty have forked Steem, but you may fail to realize like I have done in the past what a pain in the ass it is to be listed on exchanges. You think it's hard to turn your hard earned cash into steem, or vice versa? It's way harder for forks, because you need tons of money (not just minted shit coins) to get listed. We take for granted the few exchanges that support Steem and usually want more, but the reality is it's not a trivial task to get listed.

SMT's are going to be something like the tribes you see popping up on steem-engine, but with the added advantage of being added to exchanges that already support steem with little effort. This is essentially going to allow tokenization of Steem, much like ETH, but with the benefit of the 3 second/free transactions, and its own proof of stake algorithms.

Steem accounts are a barrier to entry, but a very small one that's getting better and better. New tools still need to be made/refined and put into place to allow the masses to join easily, but even now it's absurdly cheap to get started with just a little bit of cursory reading.

Steem is not a huge community (when counting active accounts) to tap into,

Steem is not a huge community? Relative to who? Facebook? Because as far as crypto communities go, this is the biggest one I know of. Bitcoin may have more users, but they're not really a community in the sense this place is.