I know there are people who still holds coins in Tier 1 exchanges but the risk is really high as we have seen the top exchanges getting in trouble and once that happens it is a battle when you will get back your coins.
The reputation of exchanges got nothing to do with the protection of out assets. Hence, whether it will be tier-1 or tier-5, we should always develop the habit of withdrawing our cryptocurrencies immediately after closing the trades. I do see people are developing their own reasons to keep on holding cryptocurrencies within exchanges but at the end of the day they are the only bearer who are going to suffer if anything like hacking happens hence no reason is not going to help anyone.
This is the reason why most of the exchanges we have right now are centralized so that if there will be future problems that will occur, the certain exchange will still have to contact us and inform about the current problem so we are still given chances to withdraw our cryptos.
Why that is not possible with decentralized exchanges? Because, I remember some dex are providing optional registration along with email ids and and other details hence they also may contact if any emergency happens.