people buy a Motorola phone just because of Stock Android. If they put ZUI in Motorola they will be destroyed by themselves
Zui is not so bad, but compared to stock Android that Motos now have, it's no comaprison. I own two Zuks and custom roms fly on them, while Zui is marginaly slower. I would never ever install Zui on a Moto Z for example. The only thing that really sucks on custom roms and is quite good on Zui is the camera. Everything else is much better.