So, my last design manager was all about function over form, you know, "design, not art" kind of vibe. It got me thinking, why can't UX stuff be visually awesome too? Usability and pretty interfaces, are they like mortal enemies? What do you guys think?

it depends. Theoritically he's/she's right. That's what lecturer teach also in the design school. But it depends on the context and his/her character and skills too...for example if we build software for hospital maybe the needs of visually extreme appealing is lower than any B2C

So, the idea was to make buying a used car feel all modern and cool, like you're getting your dream ride, you know? But the whole thing ended up just being way too serious and boring. In the end, it was just another online car seller.