Luther from The Warriors remains one of my favorite villains because he's unabashedly one dimensional. When he's finally asked why he shot Cyrus and set up The Warriors, he says something to the effect of, "I dunno. I just felt like it!"
I'll take a super one dimensional villain that the film knows is one dimensional over a one dimensional villain that the film is convinced is deeper and more interesting tan they really are, giving them way more screen time and portentous dialogue than is warranted.