Transmission is as much a Gnome as a KDE application. It has both Qt and GTK clients that look the same.
Brasero looks as complex as K3B.
I understand that Skanlite can look intimidating (especially on the Image Intensity properties), but Simple Scan seems simplistic. Scan source, scan mode and scan resolution are important properties when scanning and it's very useful to have direct access to them.
The default view in Digikam is not so different than that from Shotwell, a folder list to the left and the corresponding pictures to the right. The metadata widget is not opened by default.
As jstanek pointed out, even if some things could be made simpler and more polished, it's not so much that KDE doesn't have a clue about design and GNOME knows its stuff, but that they have different objectives. GNOME tries to be as simple as possible while KDE wants to give you power in the friendliest way possible. It's apples and oranges.
I feel uncomfortable with GNOME because I think it treats its users as perpetual newbies. I understand that a person's first use of an application should be made as simple as possible, but then they should be able to require more from their software if they want to. There are some things about KDE applications that maybe you won't find a use for at first, but then you need them and it's great to have them at your disposal.
I don't want GNOME to be like KDE, it's good at what it does even if I don't like it. The reverse holds true, too.