Not saying I don't believe you, but do you have a source for that 90% claim?
https://riverbankcomputing.com/software/pyqt/intro https://electronjs.org/
Your eye will probably be more attracted by the good design of the electron website.
I'm not saying an app should be only good looking, but it's clearly a major part.
[1] http://ixd.prattsi.org/2015/04/response-time-is-speed-the-ul...
It drives engineers batty, because it's often irrational.
Just because something is irrational doesn't mean it doesn't have a huge impact on something like adoption.
If we didn't care how things looked, we might all be wearing google glass.