I don't just mean filtering out the spam; that's a hard problem on its own. But the good-click metrics... if serving up reddit and quora links at #1 makes more people satisfied with the first result, defining satisfied as 'reads the #1 page and doesn't go back for more', then...
What's wrong with that metric?
That isn't a rhetorical question. It's tempting to claim the users are wrong to prefer it, but not very nice. Why do they do so?
It does not, what google is optimizing for is ad click-through not organic results click-through. The whole model is you will search for X see a couple of ads and a sea of bad results and opt to click on the ad.
It's the same reason that if you search for "graphics card" on amazon and sort by price you will get 20 pages of "Graphics card Holders" and "Graphics Card Elbows". They want you to not actually use the search just click on their ad.
The problem appears to be it's hard for them to realize that people are getting fed up with the antics and are seeing through the manipulations. It's like an abuser or bully, that thinks they will keep getting away with the poor treatment of others, who they think are "below" them. At some point, enough people can take a stand, and not put up with the lack of transparency and black-box manipulations. They are going to keep demanding change or find alternatives.
Bravely flattening a root cause analysis to one agreeable-sounding villain, I'd do Goodhart's Law. Click-through rate not being a great proxy for user satisfaction.
i.e. I always clicked reddit first, I used to append reddit to my searches. But I get a very uneasy feeling now that everything has reddit 3 times in top ten. Impossible. It's a big world. It'd be like if Encyclopedia Britannica started just including the snippet-sized version of Wikipedia articles. Not what I'm looking for from that product.