HI there, I'm the creator of ReCode Project. We had some works that would not run in the browser and wanted to treat all works as equally as possible. Also, we are trying to reach beginners as much as experts and as of now Processing.js is not being taught in most educational programs. I thought regular Processing would provide full functionality and better accessibility. I suppose accepting .js translations wouldn't be a big deal, I'd just have to do some more work on the site. It's a valid question and one I think needs revisiting. Thanks for bringing it up.