Too many themes hosted on drupal.org without screenshots

Here's something I would have thought was obvious, but apparently it's not to everybody:

If your theme doesn't have a screenshot, I'm probably not going to bother look at it. I imagine most people are the same as me: lots of themes, not a lot of time to find something that does what you're after.
There are many, many, many themes available to download on drupal.org. You scroll down the list, thinking 'yeah, that looks nice!', 'I'll grab that one'. No screenshot -- no idea what your theme is going to be like.

Maybe there's an issue with access roles that's preventing people from uploading a screenshot? I can't imagine why so many themes are posted without one.