Registration module is planned at some point. It just never really made sense given most CB registration pages are not simple 5 field forms. They've dozens of fields, plan selections, conditions, tabs/steps, etc.. and none of that really fits in a module position well. For your usage I'd just link to the normal registration page and put whatever landing text you need in a module above/below/around the registration page. If you need HTML on the form it self you can do that using Custom HTML fields.