The only downside is, that the devs have to maintain it (sometimes during developing a new Batocera version Kodi breaks, and someone has to fix it or if a new version of Kodi has been released, it must also be properly integrated into Batocera). That’s why there already had been some discussions to abandon kodi and throw it out of batocera, because maintaining does take time and effort, and there are not enough devs (and sometimes motivation) for all the work, that hast to be done. The features and supported devices have grown over the time, so that developing/maintaining/testing etc. takes more and more time. That’s why it would make sense, to abandon things, that are not useful or not used by many people. But regarding Kodi, there hasn’t been a final decision yet.