I can't be the only one that dislikes KDE's typography. I see that notification pane and aside from color, nothing gives it typographical hierarchy. It just looks odd to me.
All the UI and UX in general looks like it's from 2007. I know that it's volunteer work and I don't want to downplay the generosity of those who contributed to it, but I do wonder what's causing the delay in catching up to modern aesthetics. Is it a technical issue? Is there too much bureaucracy to overcome? Is there a shortage of UI and UX developers?
In short outside of the bizarre software/tech world very few subscribe to the idea that intellectual property should be shared and used freely.