Because of fragility or because costs of the material? Gold is one of the earliest metals used. I don't know out of my head what alloys (1000 BCE!) they could have used to create sub-milimeter wall thickness (0.6mm!). If they had been able to do this out of iron, it would be dust by now. Remember from Chemistry class? Gold does not react easily.
"The rolex watch was an instrument to calculate the time of the day and time of the year. It was worn to ritual conventions, dances and mating rituals. Thus it's rather primitive workings compared to the electronic and quantum technologies this civilization had access to it's value derives from the precious metals used and in the craftmanship needed to create this artifact which is in its working on par with the high technologies of this era. It was also worn by James Bond."
but the "ritual" part - I think the definition of that word is too broad if you can say that a Rolex is used for "ritual purposes"
Anyway the German Wikipedia page about Goldhüte [1] says the ritual significance was attributed because there are tomb paintings depicting similar hats being worn in some religious/cultic context.
[1:] https://de.wikipedia.org/wiki/Goldhut