Hey guys, I'm the guy who wrote most of the code for the WordPress plugin checker.

I just want to point out that it's not really a "ranking" system -- lots of plugins that show up with problems are well-used, well-liked, and work fairly well. But we wanted to provide a resource to plugin developers to check their code against common development mistakes (something I've personally learned after lots of trail and error).

But interesting idea about the theme checker. It wouldn't be very hard to add that functionality as well.