My argument to follow your analogy is.

It's not a 2^16-sided weighted die. But a 2^16 - 1 sided fair die.

I am not saying there is no bug. I am saying the bug has no practical impact.

Sure if you are that one guy that is getting these values raw from the instruction and comparing to zero for some purpose then you are in trouble. But I am pretty sure no one is doing that, especially given that the bug surfaced after 6 years of millions of users.

I can imagine someone doing a

  pick = rnrand16() - 0x7fff
  if pick > 0...

where these are not equally likely anymore (I may have an off-by-one anyway ;)).