As I alluded to earlier, it ain't broke because a tiny fraction of the forum membership uses or is even aware of the thread rating system.
We know what works: If the seller leaves out information, you can ask for clarification (location, price, what's included, etc.).
Beyond that, if you're interested, but at a lower price, PM. If you wish to inform the seller his ask price is way off market, PM. And if you're not interested, just walk away. What could be simpler, or fairer?
We have a system in place to give feedback on transactions. Why do we need feedback from window shoppers?
Buyers are free to walk away and vote with their wallets! And if you see a seller bumping a thread many times and there is no interest, that tells you the community thinks the item is overpriced.
On a side note, I find it amusing that I am having this discussion with guys who fancy themselves libertarians! ;cf