I'm running two websites, one self-hosted and, recently, another with wordpress.com. I was quite shocked to discover that the available wordpress.com themes are not only limited, but the best and most customisable themes are not among them.
Themes such as Suffusion or Weaver are a must. Without highly customisable themes such as these, you're extremely limited in what you can do with wordpress.com hosting.
Now, even if one buys all the upgrades, with self hosting you can do everything you can with wordpress.com and it has a number of advantages that make it more versatile:
- You can use and modify any theme
- You can use plugins
- Fpt access
The only drawback is that it requires a little more technical knowledge. Even when buying the wordpress.com updates you're very limited in what you can do; why not buy self-hosting with the same amount of money?
That's why I believe wordpress.com needs to include the most versatile free themes available. This would increase the appeal of worcpress.com hosting.