My personal opinion is if the artwork was lawfully obtained, in the absence of a license with terms to the contrary, it's as open for fair use as any book on your shelves. Now, if a company never had any terms authorizing such use but then suddenly pulls it on millions of people without permission, that's class action territory. If someone outright steals art for which the terms of access prohibit commercial use and then use it that way anyway, again you're looking at valid causes of action.
However, stuff that's just publicly available and accessible without having to agree to shit, tough. Unless the derivative use is not transformative, or actually does copy specific elements directly, I don't see the issue at all. Butthurt isn't an issue.
I'm sure that courts are going to disagree on this in the coming years, though.