Honestly, I dont see how it is Kraken's responsibility to compensate these folks. Its business, its a risk! No one forced them to put their coins on margin call. When I joined CB I knew there was an option for that, but I also thought "You know what if the market dips and then rebounds quickly I would be shit outta luck... so to hell with it ALL IN if the price hits zero it hits zero."
If you want to know if suing Kraken is just then just think about it this way if these people tripled their money due to the attack instead of lost most of it, would they be suing to give back what they made?
Yeah, you are right in a way! Good point!