At present, individuals pay to file and refile and, once granted, hold the patent until it is challenged in court. Since, as has been pointed out several times before, their operating budget is predominantly (if not entirely) derived from their filing fees, the economic incentive is to encourage people to FILE AS MANY TIMES AS POSSIBLE - they make it difficult by rejecting patents, but only artificially so, as you can simply refile a modified patent with a new fee for reconsideration. After a rejection or two, they are likely to approve, since they don't want to DISCOURAGE you from filing at all - that would take away a revenue stream!
What if they instituted the ability to file a counter "anti-patent" displaying prior art and obviousness? Such an system would essentially "crowd source" the entire patent approval process and shift the balance of their incentives. By allowing individuals to submit prior art and obviousness research for a small fee, they can streamline and speedup the entire patent review process (for both new and old patents), lower fees for filing while increasing their revenue, decrease their operating costs (thereby maximizing profits), AND present themselves as "open source, modern government" with maximum transparency!
With this new system, to maximize profit, they must ensure as ROBUST AND PUBLIC DEBATE AS POSSIBLE.
If people can present counter evidence to a patent, then the patent will be reject/'on-hold' by the "reviewer" until the patent seeker files their counter argument against said claim. If they can't, they've lost their bogus patent and no one is worse off (though they may be free to refile, and the process begins again, but with precident from the counter-patent filers...)
"But wait!" (I hear you cry) "If they essentially crowdsource patent applications for us to do THEIR work, why do we need USPTO in the first place?!?"
Patience, Grasshoper. For now, they still are needed to be arbiters of the evidence provided. But one day... One day...