alphawolf, honestly this is the question that most plagues me. They had to know it would shake up the webmasters who run legit sites...hence the theories that this was done in part to get more webmasters to buy Adwords (which I don't buy; too much negative aftermath).
You could conclude that they don't care...and I believe that they don't care about spam-masters, but I expect that they care about the others...it's the others who buy their services, act as unpaid PR agents, etc.
It could be testing and feedback, but they could have got our feedback without releasing this to all of the datacenters...and they could have tested it on a public server without going to all of the dc's.
I really don't get it.
It was either a colossal miscalulation (even 80 PHD's can be wrong)...or more likely there's still something that none of us have thought of, or that some thought of, but most have have not latched on to. eerrggh.
Anon27, no legit insight, just a pathetic guess...if I were at Yahoo!, it wouldn't have taken me too long into this update before I picked up the hotline to the Plex and said "Hey, you smart guys can jerk your own customers around if you wish, but we prefer to keep the best, most recent, and most stable set of results you have for our feed...given that we prefer to treat our visitors as long term customers..."