I mean, that’d be a major GDPR breach, be hard to extract any signal from because queries will usually be coming from a relay or from behind a NAT so you can’t tell who the query even originates from, and DNS is cached heavily too so you only get a small fraction of the queries anyway. I’m not seeing a way the calculus work in favor, basically.

OTOH the question of why they’d even run a public DNS is interesting, yeah. Running a public DNS is cheap and helps the Internet work better, and they make more money when the Internet works better since that adds up to more page views. Less charitably, though, it’s possibly just a thing from back when they were an engineering company first and foremost and did that kind of stuff, and now they can’t turn it off without breaking a lot of things and causing a lot of costly anger.