I was browsing the Drupal Theme Garden a few days ago and was reflecting on how incredibly boring (if not ugly) a large share of the themes looked. Out of all the themes I viewed (over 50), I might consider using only 10 or so on a production site for a quick project that I didn't want to create a theme for.
Later on, I read this post on Steven Witten's blog [Acko.net] from 2007, and read through every single comment, because I am extremely interested in the issue of Drupal theming. If you are at all interested in helping Drupal be more themeable and appealing to designers, you must read the post linked to above. Go ahead - read it. I'll wait...
...okay, now that you're back,
A few of the comments in Steve's blog post deserve a mention...
From the blog posting itself: "Not enough Drupal people are savvy enough about theming and design to help out with even small tasks (like a banner) or even give quality tips and feedback on other work. The result is that theming and design receives little attention. Most contributed themes and sites could look a lot better, if they just themed it some more. And getting patches into core that give the defaults a little more oomph is tough, as they are often considered to be useless embellishments.