I know you weren't making this connection directly for me, but just for the record I have actually been a big fan of Twitter for quite a while ;)
I do see your points, but and I'm not saying my suggestions would make it a more popular site, or give it a better chance of making money, or a better chance of lasting longer. Simply that it would make it a site that I would enjoy more.
And obviously I can see that my Bieber example was humour, and my point wasn't disagreeing with that, simply that a site for of actually insightful answers would, to me and to many others (not saying the majority) would be far more interesting, than a site full of random humoour.
Would it be a waste to get pg to write just a sentence? Perhaps, but if so that means I have picked a bad example. I've seen many examples in the past of something quite complex being explained in an easy-to-understand one seentence way, which would have left me wanting a lot more had it been in my area of expertise, but in fact I much enjoyed.
Here's an example, the P = NP problem. Sure, some people will enjoy reading pages and pages about this, but others not so much. A well-worded one sentance on why people care about it could therefore be interesting.
Add that to many other topics, and essentially you're building a database that lets people learn a very little about a wide range of areas. What was the actual logic behind schrodinger's cat, how do birds fly, why is moore's law the case?
I would enjoy browsing through that, I think. And, hopefully, some of them would be "I already knew that", some would be "I don't really care", some "that's quite interesting" and some "hmm, I need to go find out more about this".
So really I wasn't trying to slightly alter this concept, I was pitching a totally differeent purpose of an almost identical website, that in my very subjective view would be better.