I'm guessing that if we decide to do it we would want to do it well, with detailed support and documentation. For example if a modder wanted to add parts/organelles their mod would just have to add the items to the respective lists and then our system would make sure they show up in a manner that looks good and generates scroll bars if necessary etc.
Another thing to consider is both a "workshop support" like system for mods and our own in-game browser for in-game creations. I say this because, while steam workshop and similar systems are very good for mod distribution, all mods using this system that I have ever seen need to be loaded in before a game is started. If we want someone to be able to search other players' creations and plop them into their game on the fly this system wouldn't work very well, not to mention files like creatures and creations shouldn't need the game to be reloaded anyway so no reason to force players to do it.