are our shares getting smaller
All SteemPower holders receive a constant tiny supply of inflation-fighting stake. In addition, the price lets us know. If more people want to sell than buy, the price erodes. So, its a difficult question. In a sense, yes.

Those who power up and hold Steem keep the price up. Those who sell, drive the price down. We also need volume and utility, so it is fine that some do sell.

Steemit's face is their website, so if they don't improve it, they are losing out on potential Steem investors who would increase the value of the shares

This is a guess, but I think they would be more worried about getting business investors than end-user of the site. That is why we have to act like a team and help hold the community together.

_, I believe that it would be really hard to create many of the functions that are proposed without according changes to the blockchain. _
I don't know enough to hold any opinion on this! Interesting perspective.

_ fact, the blockchain doesn't have any ability to order posts by number of comments, number of votes, etc., and there is no way to whitelist low rep users, blacklist/block spammers, etc. (not globally at least)._
I don't know for sure, but I think what they plan on for communities may address some of this. Again, not anything I understand well. :)

It is an interesting thing that we have a chance to participate in becoming stakeholders BEFORE the businesses even come. I think many here are so focused on the blogging site they are missing what is coming.