There is a place for Quora because it has helped build a community of users that provide extremely valuable advice / answers in a nicely presented format. I'd pay atleast $10 USD per month to save Quora if there ever was need for it.

Unlike reddit or yahoo answers, answers are often provided by real members as opposed to hollow or anonymous accounts and it also serves as a collective wisdom center for past experiences of other humans that you can refer to.

I'm unsure what the correct mix is, but Quora is at the sweet spot of:

twitter + r/askreddit + yahoo answers + ask HN

-> Want to know how to transition from engineer to a job at a VC firm? Well you have folks like Leo Polovets (Current VC, early Linkedin employee /Engineer at Google, Factual) provide extremely detailed answers that are well written and more or less permanent. You know the dude is qualified and is somewhat credible [0].

-> Want to know how Stripe got its name? Well you are in luck because Stripe CTO tells you exactly how [1].

-> Where else can you ask about the evolutionary purpose of menstruationand get a response from a PhD in Zoology? You know its on Quora [2] (unless you want to get trolled on reddit).

[0] http://www.quora.com/How-does-one-move-from-being-an-enginee...

[1] http://www.quora.com/Stripe-company/How-did-Stripe-come-up-w...

[2] http://www.quora.com/Menstruation/What-is-the-evolutionary-o...