Seriously Simple Podcasting started as, and is still very much, and open source project. We welcome all input and contribution from the WordPress community and want to do everything we can to encourage that.
All you need to do is head to the GitHub repo where you can fork the code, make some improvements and send a pull request. All pull requests will be considered, and contributors will be acknowledged in the plugin changelog. Not to mention a few shoutouts on Twitter!
If you would like to suggest features for the plugin then you can either log an issue on the GitHub repo, or log a new support ticket.