If they simply rob without a weapon, there are generally robbery charges with lessor penalties.
There is a clear uplift of risk/jeopardy of death or harm when using a weapon while committing robbery -- the person committing the crime is only partially in control of the outcome: the victim, witnesses, law enforcement interruption or an infinite number of random events can all trigger the harm (which is attached to the original crime). But this is well known and a decision the assailant made before committing the act -- they inherently are willing to kill or harm the second they chose to use the weapon in the act even if their intent walking into it was not to kill specifically.
I guess we just disagree, but I am very happy the laws and punishments are written to align with my POV.