I'll keep aside the logic of whether I like what they are doing or not and ask if they have any other option.
The die has already been cast in Quora's case, from what it looks like from the outside (I'm speculating wildly here), it looks like the company realized a while ago (around the time of the Charlie Cheever ousting saga) that they're growing at a pace much slower than what is expected out of them.
A $11 million series A to $50 million series B usually fits the profile of a company in hyper growth stage.
Is Quora a company that fits such a profile? All pointers (admittedly imperfect) say 'no'. Even going by their latest feature, blogs, it would appear that they're also running out of tricks. Such a feature is often a clear indicator of the flattening of user growth, leading companies to chase down usage growth aggressively to make up for the decline in the former.
But a $50 million series B should fly in the face of such an assumption. Well, maybe not. Money can either help you unlock known avenues for growth or it can help you explore unknown avenues. Either option buys time, but with different ends in sight. DAngelo putting up some of his own money certainly points at the latter. It looks like an attempt to buy time to explore.
While it is hard to wager what their burn rate should be, it is probably not enough to burn $11 million in two years. Even with the really nutty assumption that they have actually burnt $11 million in 2-years, with the current round they should be good for another 2-3 years. That's enough time to focus purely on how to massively grow the product without having to worry about how will you pay the bills in the coming week.
With that perspective in mind, it is easy to see why they're less interested in being a warm-and-cosy small community with great answers that pushes all the right buttons with the power users.
Their road ahead is a choice that's already been made. Where they will get to on that road, I don't think anyone knows yet.
One thing is certain, though. They'll either win really big, or will flame out pretty badly. They've already boxed themselves into a place where there is little space in-between.