I strongly feel "the consequences are of nature and totally fine because my magic is of nature and therefore I can't do anything unnatural with them" is a very un-druidy way to reason.
It is literally how it works, though. Druids get their power directly from nature in most cases. Wouldn't you consider it "unnatural" for an elf to turn into a bear? What makes that more natural than giving an animal greater intelligence? Or heck, what makes buffing an animal's intelligence less natural than giving a human armored skin made of tree bark?
It is because they are druids and their power comes from nature that makes it natural.
