by providing them as GPL only my reasoning was that it may help promote or convince people to produce projects under the GPL.
Right, so it comes down to a choice between encouraging open-source projects (under GPL) vs. releasing something under LGPL to encourage as widespread use as possible. Both are fine goals. I think that the reality is that far more people work under circumstances that prevent them from using anything other than LGPL or commercial libraries.

I was happy when Nokia opened up Qt to LGPL, but I still pay for the commercial license just to avoid having to figure out how to build all of Qt in the absence (at least as far as I have been able to ascertain) of any scripts published by Qt to build it. Perhaps this will come with the switch to CMake for 6.0.

Is there anything in particular that you'd be specifically interested in?
Probably the component system, dock windows, and ribbon in that order.