Hey Luke, thanks for reaching out, I'll gladly help!
Yes, we added that widget in the create-new-post page for our users to find and include quality, related posts from around the web. The thing is, once you start to link out to other similar bloggers out there, your blog is also included in our Recommendations Pool (i.e. our network), which means that your blog posts are also eligible to be used as related posts by others who use one of our 4 products (on W.org, WP.com, Blogger & TypePad blogging platforms).
And yes, we are working hard to make this widget optional. We expect to release the updated version in the following day(s). Please bear with us!
But if you wish to act now, the only suggestion I can offer you at the moment is to revert to the previous version of our plugin (please mind that the v2.7 is the one you're looking for), which was widget-free. You can get it under the 'Developers' tab on our WordPress Plugin Directory page. Here's the link: http://wordpress.org/plugins/related-posts/developers/ [ link replaced with actual link, please do not use short links here. ]
I sincerely hope you'll find your way around that widget and that you will like our new addition, but I can completely understand if you wish to revert to the previous stage of our plugin. Either way, do let me know what you think or if you have any more questions what-so-ever — I'll gladly help you out!
Take care & have a nice day!