The dialog is way too small by default. At minimal zoom, it displays only about a dozen items in a directory and there isn't enough space to display all the details for items, since two-thirds of the dialog width is taken up by the bookmarks and preview sidebars. I think the bigger GTK open/save dialogs are much more adequately sized, plus they use less space thanks to CSD ... well, that and the fact that their preview sidebar usually doesn't work for most files. I have the KDE dialogs set to 900*700 via regex window rules.
Yeah, it really is. I need to finally figure out what the heck is going on here.
Also gtk-style hiding scrollbars could be really beneficial for these cases. The current bars take up ~30-40 pixels of space horizontally in the dialog, all the time. It also clutters the interface. It would help to have an autohide scrollbars option in Breeze. It is possible to show that an view is scrollable without an always on scrollbar. GTK does it by adding dashed lines to indicate possible scrolling directions. I think it's a good solution, at least as an option. (In general I think it would benefit KDE to just go right down the line and look at all the things Gnome does differently with the UI, then adopt the good parts if feasible. Many of UI problems have already been solved by Gnome.)
Note that most of KDE's UI is just Qt widgets. While KDE developers can (and do) submit Qt patches, they need to work on all platforms. GNOME developers have full control over GTK and don't have to care about Windows, macOS, or mobile systems. That's why GTK is ahead in Linux hardware adaptibility (pen/touch input). Looking is easy, but actually getting Qt changed is harder. More contributors are needed.
fixed? https://phabricator.kde.org/D25986
Ah yes, thanks for finding the bug report for this. I missed it before.