People have been making the argument that QT or Wx should be the default for a while, the problem is and remains A: licensing or B: complexity of shipping "batteries included" distributions. For A, PyQT's license might surprise you: [1]. Python can not distribute this with the rest of the essentially-BSD-licensed Python distribution. For B, for instance, none of the linux distributions particularly want "Python", which is often a
base requirement, to pull in either of Wx or QT, both of which are quite sizable, and require their own stack of other things to come piling in too.
It's sad, but I'm not sure how to resolve the problem, and nobody else has been either in the past 10 years.
[1]: http://www.riverbankcomputing.com/software/pyqt/license