In T15613#279133, @ngraham wrote:

because the subwindow for selecting a property to change completely closes after setting every single one

Thankfully that's like a one-line change. :) Feel free to propose it in the form of a merge request or a bug report.

I feel I should pitch in a little bit on this, because I have had some very frustrating moments with some KDE software that's been changed recently to be 'more user friendly'. I know this isn't exactly what the proposal is about, but I've seen the sorts of people who do promote this type of thing also making the same sorts of decisions in other software.