well Qt Quick can do that, it depend on devs to implement this feature.
anyone can tinker with the source code. and publish it. as long as you provide the source code that can be verified to not contain trojans then im sure the guys at bitcoin. org would put it along side the non skinable version. allowing people to choose.
even if the guys at bitcoin.org dont add it, you can put it on another site that is credible and been verified by a credible person/people.
So much money going into The Bitcoin Foundation, and so much going to some of the core dev, why isn't stuff like this getting done?
microsoft employs hundreds of people to make microsoft word/excel, they come up with a new version every couple of years.
bitcoin has gone through 8 mini version numbers and a few bug fix versions inbetween.
it is also important to know that bitcoin is dealing with wealth/value, and as such beta testing updates is more important then betatesting microsoft word.
so with all that said be proud they do something atleast. and if you dont like the amount they do, join them. submit some code and get it into the next version of bitcoin-qt.
and if you dont like bitcoin-qt team, you can always submit it to another app like armour, etc. or make one yourself using other peoples source code as most apps are open source.