For a very simple reason you have to understand: only 3rd party developers approved on the Market Place can have access to Asobo technical support, and we need such support to bring this product to completion. So you see, RXP is an “Official 3rd Party Developer” (see my badge), but we don’t have any support at all, are not allowed to sell anything on the market place either*, and the community can’t enjoy their favourite game with their favourite add-ons, or at least if not favourite, different and answering the needs of the customers looking for something else than what is discussed here:
Dearth of genuinely appealing content in Xbox marketplace
*and to top it all, since yesterday: