I know what you mean, but there is surprising, err, "design value" in keeping the layout minimal.

In any event, the simpler the layout, the less work the browser layout engine has to do, and the snappier everything is.

I don't think the issue is that they're minimal. These lack in design aesthetic. They are just plain ugly in most cases.

You can can certainly have a minimal design while maintaining a high-quality aesthetic: https://dribbble.com/search?q=minimal

I believe they intend for you to use them as building blocks. You can use their layouts to get your idea on the screen, then add additional CSS in order to 'make it your own'.