First of all, you can't use a Cintiq without a computer.

Secondly, when people say "great for consumption, bad for creation" they are referring to the design of tablet operating systems like iOS. Artists who use a Cintiq typically have multiple monitors and are multitasking with many different applications (Photoshop, Illustrator, ZBrush etc). This sort of workflow is just not possible on an iOS, WinRT or Android device.

I have a Cintiq, I always somehow end up using my PC, because I need to still use my mouse to get certain things done precisely (For example compound Boolean operations for Logo designing). But hey, yours is a very good point, but it is rather very specific to a certain type of artists (In my opinion).