Thanks for the feedback, Renan. The core has 188Kb minified and 52Kb gzipped. The size is mainly growing because of the way contenteditable works in browsers. We're mainly using it just as a way to input data from the user and all editing operations are being handled internally so that the output is always the same in all browser.
Indeed, it could go much smaller if we'd move the UX out of it. I totally agree with that and we actually discussed this couple of weeks ago.