I believe a lot of well-known people will start deleting their account as well. I don't think that Selena Gomez, for example, is comfortable with her pictures being used for advertisements without her consent.
I highly doubt that just because its supposedly covered under TOS that they'd start using celebrity Instagram pictures against their will. There are plenty of reasons for them not to.
Yes, but "trust us" is not a good disclaimer on a legal document.