It feels like a firehose of users - mostly from the developer community - is being aimed at cookie cutter sites and a lot of wishing for the best is going on behind the scenes.
I've outgrown games perhaps, but committing didn't require anything. Maybe if it had cost me 1000 Stack Overflow reputation points I would have thought twice about signing up? If it did cost that much, it would be a high barrier to entry for non-programmer-non-stackoverflowers and the site would get less people committing (resulting in the "ghost town" effect).
Most good communities, online or off, build organically and over time. See HN, Reddit, MetaFilter, Digg, or even Stack Overflow itself (in its original form). Getting hundreds of users to "commit" to forming a community on day one is a recipe for disaster and will end up in a place people dip in and out of rather than truly care for.