They can be a lot of fun. But this is how I'd do this so everyone is pleased: -Keep them in tune. Growing flowers is probably where I'd draw the line. Exploding corpses, melting enemies? Sure, go ahead. Making enemies dance, tooting sound effects? Nah, doesn't fit. It should feel like something that could happen in the universe. Also, take care of not making them annoying or repetitive. -Consider making them actually useful, even if not as much as normal mods. For instance, the one that grows flowers could add +20% crit damage to the weapon. Of course this isn't the kind of mod you use for meta at all, but at least that way you are not spending a slot exclusively for aesthetics. Or just add an auxiliary aesthetics mod slot. -Keep them out of reward tables, specially the current ones. Maybe add them to a new table, make syndicates sell them, put them in baro's stuff, and of course selling for plats in the market. That will keep the attractive of exclusivity too. Nobody wants another ayatan anasa case. -Toggleable in each user's settings so if people doesn't like them they won't be bothered.