The point is changing defaults.
Many state that KDE Plasma UI is “outdated” (https://discuss.kde.org/t/does-kde-need-to-hire-professional-designers-ui-looks-outdated/). This was one those decision that I think makes Plasma more coherent.
This post is kind of refer to Nate’s comment that people don’t mention specifics (Does KDE need to hire professional designers? UI looks outdated - #23 by ngraham).
Nate Graham: When this topic comes up, I find that it usually goes better if we narrow down on specifics. The more general the critiques remain, the less actionable anything is. We end up dividing into camps saying “make it more modern somehow!” and “it’s fine the way it is!” and this doesn’t go anywhere.