... but without a company and a community of hackers constantly working to add more backends, more instant answers, more !bangs, and give you better results. So why would I use it?
You don't need a company for building a meta-search engine. And most importantly, if you value privacy, you want the whole meta-thing to be open source, always.
My point isn't about privacy. If you really are that privacy-obsessed, than building your own meta-search might be the best option for you. For me, I like the fact the DDG's meta-search is incredibly well featured, with instant answers, and many backends for that, its search, and !bangs. So if I'm not that obsessive about privacy, why would I go to the trouble for a weaker search with less features?
Set it up remotely and you basicially have your own DDG.