It's stuff like this that reminds me that the internet is in many ways still in a loosely regulated, "Wild West" state. This is pretty clearly willful destruction (I.e. vandalism;
https://legal-dictionary.thefreedictionary.com/Willful+damag...). It's illegal in the real world, and should be illegal in the digital world. A lot of people are saying that organizations that had these DBs in public "had it coming", or "now they'll learn." What's a real world parallel for this? If an organisation is putting its customers at risk, you can report them. In these cases, companies with insecure data stores are putting their customers at risk by exposing their data. Is there anyone you can report them to? Is there any organisation that will hold them accountable to actually make changes?
I'd also note that not all DBs contain other people's data. Those have no moral concerns with bring public. There is a risk that someone will destroy it, but I'd say that's the same risk taken with public art or something. Yes it's public; yes someone can destroy it; yes it's illegal for someone to destroy it (even though it's public); no, the fact that it's public is not illegal.