And more critically: I realize that this is your baby, and you have had a large amount of involvement and personal investment in these projects over the last several months. However, you're coming off as both very defensive, and very dismissive of the criticism so far.
It's surprising to me that YC would unveil its next batch of startups, and get such a "meh" reaction from the audience. That indicates a problem worth investigating, either in the community here, or in the specific projects that were funded this time 'round, or in YC's goals (specifically whether those goals might be diverging from those of the HN community).
In fact, I explicitly tell YC startups to explain themselves to investors as "the x of y" whenever possible. See point 14:
http://www.paulgraham.com/investors.html
The reason I've been so contemptuous of some of the comments on this thread is that I've been seeing the identical comments on web forums for 5 years. That's how I can be sure they're not a sign of a problem. They're just the same type of people making the same type of comments that always get made about newly launched startups.