I agree that usually one uses a higher level API, but I've worked on commercial apps that use Metal both for graphics and compute. The code is not so unweildy as is suggested here. An old triangle test app I have here shows only about 100 lines of graphics code.
Of course, a lot of this code is code you only write once and then abstract on top of. Metal just has a lot of that abstraction "done for you" because it's only designed to work on a closed set of hardware profiles.
Vulkan requires a lot more signatures in triplicate and setup rituals. Not a bad thing, just a different target.
