Did you see or use KDE4 when it was new? KDE4 was a radical departure from the earlier design, which looked like a mimicry of Windows Vista for "reasons".
By 4.10 or so KDE 4 had matured to KDE 3 level and this hasn't changed with Plasma 5.
The problem with newer versions of GNOME is, you get what they give you and you better like it cause that's all she wrote.