The only issue I have with the "free" downvotes is that some people with high hive staked use it often for someone they don't like or agree with. The article quality is fine and everything but yet it gets a downvote because they feel they don't like you. It's legit stupid and it's more damaging then the feeling of your random downvote. I know it doesn't happen often but it happens and there needs to be some type of measure against that as well.
Fully agree though that gaming and spamming the system is a very real possibility if you take the free downvote system away. Double edge sword type deal but honestly to me that really shows the character of a person behind the account.
RC is always kind of an issue. When someone new joins out of a non delegation onboarding it leaves them wondering and not understanding why they can't post, cant post often or they can't comment. You only need about 10-20 hive to really have enough but as someone brand new to Hive that would mean $5 - $10 I have to pay just to interact with the platform. A major hurdle for onboarding. Hurdle 2 for onboarding it's actually not easy for most people to get their hands on hive. Limited exchanges, limited swaps and no Fiat conversion that I know of. Perhaps a front end swap right here on hive that blocktrades has but making it more prominent and accepting more crypto coins could be a helpful option on this front.
Removal of rewards however I think would kill the platform as there really are not many other use cases for Hive right now. Perhaps later down the road when Hive has more use cases such as gaming, swapping, other front end blogging systems like palnet, leofinance, proofofbrain etc. and more. At that point I see Hive being more of a background token you stake and hold and use to buy things as the main currency but all the tokens under it such as LEO, POB, PAL etc are like the ERC-20 tokens of Ethereum.
I don't have all the answers and I haven't dug into it much simply my views from what I know so far and interacting with Hive/Steem over the last 5 years.