Well, that's your choice if you should or not. I don't think many users would want to pay money for something as small as a preset. However, I'm not saying that users wouldn't pay money for presets but I'm rather saying that from what I believe, only very few would pay money for these types of stuff. FeralHeart is a free game, you knew that, so maybe the reason people don't do this is for that reason.
There's other ways of approaching this however, such as donations. You use whichever method works for you. If you feel donations are the way to approach this, or paying for presets, then do whatever makes you feel better.
On a complete different note, I believe this topic should be moved to game discussion as you're not stating a idea of money for presets as a community, but rather asking if you should or not. You may argue saying that it should be here because it's your opinion, but I personally think it should be moved. Locked if needed maybe. Although, this is not my place to say this since I'm not a moderator, but it's just what I think.