It may be the anthropologist in me, but I feel that mummies need to be "sacred" in some way, as opposed to just generic "tomb guardians."
Those mummies aren't just linen golems stationed there to beat up on avaricious adventurers. They're people (or sometimes beasts), sacrificed, sometimes willingly, to provide service to their lords, forever. They're holy and special, and their main goal has nothing to do with potential grave robbers. When a grave robber comes along, it's an issue they resolve, but that's not the purpose they were created for. They were created to be
eternal.
Related, I feel like there's little possibility for a mummy who is also some sort of royalty in this narrative, preserved to be reborn in flesh at some later date. A mummy created to be re-created. The mummy they describe isn't about achieving immortality, it's about greed beyond the grave. Which is an issue for me.
The lich is OK. And I might be a little overly touchy about the mummy.