Verification doesn't matter, unless you need to for limits etc. Majority of those disabled accounts were verified and if unverified accounts are a problem they wouldn't allow them.

Bittrex has been showing the problems and the ugly side of centralised exchanges. Closing/disabling of accounts without warning or explanation and delisting coins without a clear reason.

Disabling accounts this way means it could be anyone next, doesn't matter what you do if they want to they can wihtout explanation, you money is at their mercy. Delisting of coins, notably bitshares, raised alot of eyebrows. I can think of a ton of other coins that are dead on bittrex that should be delisted way before bitshares. Again they can do whatever they want and don't need to say anything sadly.

You have to judge for yourself whether the risk of using bittrex vs the possibility of suddenly having a disabled account and loss of money is worth it.