There are legit Android app stores other than Google play. Amazon and Humble Bundle for example. Android users should just use the same precautions as if they were installing software on a Windows PC. Only install software from trusted sources, yes, but Google Play is far from the only trusted source.
They are saying malicious code could easily be embedded into software to exploit this vulnerability. That is why they are telling you to only download apps from approved app stores. You will reduce your risk that way, but the exploit still exists.
Any OS can be exploited. Just like iOS is jailbroken, Android can be rooted, etc. The exploit per-se is not dangerous, just some applications; the same old common sense when deciding to allow an app to install still applies.
It's amazing how every single article like this ends with the same conclusion: leave your default phone settings alone if you don't know exactly what you're doing, yet people still react as if the end of the mobile world is coming. The apocalyptic tone of the title doesn't help.