If the writing is an important factor, then I would say it is better to have it not be optional, since you can focus on the character being whatever they are, otherwise you basically have to double your work and write two separate characters, or write your character in such a way where it didn't matter in the first place, but then you run the risk of having a little something extra you aren't able to write about.
Additionally, optional means you have to produce possibly double the art/animation assets, depending on how it's implemented.
Basically, it all boils down to how much work you want to put in as a dev/writer/artist.
Additionally, while having options are great, I think it's easier to market your game or whatever as "a trap game" vs "a game with trap option". Being a game with a trap option implies you have some trap content, but it's not going to be a lot compared to the rest of your content, which in my experience with people who enjoy trap content, generally you either want a lot of it, or none at all.