The reason you shouldn’t delete them is they are inherently tied to the definition of the category itself. It can cause things to break down the road even though you might not see anything right now.
Also, have you considered creating tags instead of lots of categories? Having 200+ new categories a day is going to cause some strain on your site long term, plus make it difficult for new community members to figure out where to post stuff, whereas tags are a bit more freeform and can be restricted to specific categories.