This reads like someone asking whether it's safe to leave your front door unlocked again because he read about a bunch of people using open front doors to rob them.

It never was safe, it never will be safe, you're trading convenience for safety, you're supposed to review the PKGBUILDS to ensure they're safe, if you can't do that you shouldn't risk it.

This is why I hate when Arch (yes, even Cachy or whatever is the current "easy" Arch) is recommended for new users. Arch assumes you know what you're doing, it expects you to read the manual, and it doesn't have kid gloves. You will get hit in the face by this and many other similar things, and will be told "it was in the manual".