you know how people say doctors have bad handwriting? i think it's like that for Reid. he's got so much going on in his brain that cooking and socialization skills are pushed to the back burner. doctors have so much to remember and are so overworked that they can't be bothered to write legibly.

perhaps making Reid inept at cooking or other basic skills is a way of giving his character some flaws/weaknesses that go beyond his small frame. it's like his kryptonite.