The old ways supported both keyboard and mouse workflows, on purpose. There was no reason to collapse the titlebar except for the unfortunate time when 16:9 monitors were forced on us and vertical space became precious. A time thankfully that is over.

Today I have one 3:2 and one portrait monitor so compacted titlebars are particularly poor design.

Thankfully KDE for the most part does not indulge in that, and let’s you fix window borders, but they have other failures such as hard coded button order in dialogs.