I think that's a matter of debate - I personally don't think hardware should allow any sort of memory leakage in an otherwise safe language. It also renders any attempt to move critical software out of the kernel and into user-space very dangerous.

With meltdown, the issue was definitely a failure of the hardware vendors obligation -> Kernel memory should definitely not be exposed to the process and yet it was.

I would say such a justification is somewhat of a cop-out by the hardware vendors.