I understand what you're saying and it has been clear that outside signals have been used and that big, popular sites were exempted from it. What this has done is kill the 'middle class' businesses with straight to the point info and rewarded those with pop-ups and sign here and click there, irrespective of content. And we're talking about killing sites, not pages. Of course on the niches that Panda run.
This also lets 'good' sites get away with lots of junk in the SERPs since the average is still what Google considers good, while good pages from 'bad' sites are pushed down.
Lastly the junk traffic G now sends sure isn't going to help anyone improve metrics. But Google is happy.
Ah, the benefits of essentially having one monopoly controlling everything and changing whatever they want, whenever they want to whatever they want. As long as it works for them...