Actually, a bug was exploited.
By that reasoning, I should be allowed to legally contact Amazon customer service and socially engineer access to others' accounts, then place orders to be shipped to myself. If the customers call and cancel the orders as fraudulent, I should be awarded damages in a lawsuit against them.
It's also worth noting that, if you're a person that doesn't have any monetary interest in The DAO, you don't have any right to vote for anything, meaning you're no different than somebody standing near a poker table spouting out your philosophies about where others should put their money (aka in the industry as a railbird).