From the looks of it, it seems Khrono's API may actually be significant better/easier to use than DirectX? I haven't heard of DX12 getting overhauled for efficient multi-threading or great multi-GPU support. DX12 probably brings many of the same improvements Mantle brought, but Vulkan seems to go quite a bit beyond that. Also, I assume DX12 will be stuck with some less than pleasant DX10/DX11 legacy code as well.
For example, in OpenGL, you can upload a texture with glTexImage2D(), then draw with glDrawElements(), then delete it glDeleteTextures(). The draw command won't be complete yet, but the driver will free the memory once it's no longer being used.
It sounds like with Vulkan, you'll need to allocate GPU memory for your texture, load the memory and convert your data into the right format, submit your draw commands, and then you'll need to WAIT until the draw commands complete before you can deallocate the texture. At every step you're doing the things that used to be automatic. So it's harder to use, but you're dealing with more of the real complexity from the nature of programming a GPU and less artificial complexity created by the API.