What could they do? You lost all faith in them but in reality with the way ethereum and bitcoin are structured there are really no ways that I know of to reverse the transfers once they are completed. So you got hacked which really sucks, but I found myself thinking about coinbase and I really don't know what they could have done about this. It is something ALL of us run risks with anywhere that we store our crypto. :(
I am truly sorry this happened to you. Oh, and I don't use coinbase, so I am not defending them out of any sense of loyalty. I pretty much leave my money in steem power and I sell steem and sbd and convert it to fiat to buy things as needed. I don't leave it sitting anywhere but as steem power. :)