I think Quora would have been great as a “lifestyle business” [insert appropriate sneering as necessary.] Put ads on it for logged-out users, have good SEO and high-quality Q & A, and it'll make a living for a small number of people to keep the site up. This is how Ask Metafilter works, and it is among the best Q & A sites. Metafilter (which includes metafilter.com proper) seems to provide a comfortable living for about 4-ish people (I'm guessing a bit here, I think you could find more info if you looked.)
The problem comes when the company gets funding, and suddenly it's not good enough to become a high-quality, community-driven Q & A site. Suddenly you need to generate some kind of huge exit for your VC owners, and then their recent action start to make sense.