NC would conflict with the Free Redistribution criteria of the Open Source Definition[1], and BY would be the equivalent of the "obnoxious BSD advertising clause"[2].
And besides all that, I really don't think the world needs yet another GPL-incompatible licence. You effectively wall off your code from being used in the vast majority of the ecosystem and vice-versa, and you end up with a scenario like Sun's CDDL where developers have a disincentive to work on your code due to its incompatible licensing, and they have to jump through hoops to integrate it with anything else. Unless those effects are desirable to you, you're better off just picking a compatible licence[3].
