The Nokia tablet is a "form factor experiment" of Nokia, the target of it is not GNU / linux / <insert any other form license> opposite to for example openmoko or GP2X .

It's target are mainly *users* like me who like to have a device that simply works. 99% of this audience has no interest in getting a "GNU clean" system that has less functionality (because of driver issues with some parts or so) then a system where parts are closed source "binary blob" but work as advertised (or close... ).

If GNU purists succeed in making a system that is better then the provided SW stack I'll bet a lot of people will be more then happy to use it, but until then most "normal" users won't care to much - wich is nokia's target (in the long run) audience.
The fact that Nokia is trying to make a working business model based on (partial) GPL software is only to be applauded as it will only give more credibility to the opensource/gnu/.... "movement".

bootnote: I never heard someone not buying a TV because their TV firmware was not "opensource"...