Is there ever a reason not to choose small weapons?

Currently, I'm pretty much always using small weapons on all my ships(unless a weapon doesn't have a small version) since they have better accuracy for the same DPS(as a medium has double the DPS but usually you then also have only half as many slots).

Therefore, I can't really see a reason to use large variants of weapons. Can someone give me a good reason for why I should use them?