Without proper machine learning on the individual level, DDG will never improve beyond a point. They're already kind of shitty, and even if they get millions of more queries they won't be able to improve at the rate that Google does.
It's a trade-off ('privacy' vs. 'quality') that 95% of the world doesn't give a shit about. Therefore I see this sort of move to DDG as just short-sighted and unreasonable overall.