Out of the box it does not even bind to a public internet address. Somebody configured this to 'fix' that and then went on to make sure the thing was reachable from the public internet on a non standard port that on most OSes would require you to disable the firewall or open a port. The ES manual section for network settings is pretty clear about this with a nice warning at the top: "Never expose an unprotected node to the public internet."
Giving read access is one thing. I bet this thing also happily processes curl -X DELETE "http:<ip>:9200/*" (deletes all indices). Does it count as a data breach when somebody of the general public cleans up your mess like that?
In any case, Elasticsearch is a bit of a victim of its own success here and may need to act to protect users against their own stupidity since clearly masses of people who arguably should not be taking technical decisions now find it easy enough to fire up an Elasticsearch server and put some data in it (given the amount of companies that seem to be getting caught with their pants down).
It's indeed really easy to setup. But setting it up properly still requires RTFMing, dismissing the warning above, and having some clue about what ip addresses and ports are and why having a database with full read write access on a public ip & port is a spectacularly bad idea.