It could also just be that they [incorrectly] assume their users are dumb, their algorithms are smart, and have forgotten what made them big in the first place.

It could also just be that they [incorrectly] assume their users are dumb, their algorithms are smart, and have forgotten what made them big in the first place. IIRC, besides PageRank, one of their original usability improvements was AND-ing query terms by default instead of OR-ing by default like their competition.