Bittrex violates their terms of service. I opened an account back when you could move more bitcoin daily without identity authentication or any verification. This is important since a hack on an exchange could be possible to steal the database of ID's and compromise your identity elsewhere. There is no shortage of identity thefts, and this information has value on the black market.
I had a small balance on Bittrex, so I logged in one day simply to clear it out. This time I asked that I needed to provide additional ID before withdrawing. I happen to know that the information they are asking for is worth way more on the black market than the small balance inside my account. I plan to sit back and wait until the value of the small balance grows large enough to make it worth.
If you've ever been the victim of identity theft before, then you will know that this information needs to be highly kept confidential and these exchanges have absolutely no assurances that they have any mechanism in place to protect that data. My advice is to sue them if they compromise yours.