If mummies had better apts, they'd still be fairly different from other races due to being able to ignore the hunger clock. Being bad at everything isn't required for diversity.
Mummy hunger clock is the least interesting thing about them, because it basically never matters. Because
hunger doesn't actually matter like 95% of the time. Even when it does matter it only barely does so.
Every single distinct and interesting thing about mummy is a disadvantage. That of course includes their aptitudes; humans, demigods, and mummies are all very different purely on the basis of their aptitudes. And you can say the same thing of stats, as all the Chei fans are so quick to bring up.
Yes, except you get problems where people like the gameplay of one of the terrible races, but doesn't like the sucking that comes with it.
I like the sunny days in July, but I don't like the heat that comes with it. Sucking IS the mummy 'gameplay'.
The task of winning the game is the game.
Then WHY would a race that instantly wins be "stupid"? And why do races that aren't Centaur exist, since by your reasoning, they all have bad design?