The flipside of being so small and dense is that was fragile, which is a problem when you're trying to preserve something for a millennia. It was also undoubtedly expensive, meaning few were produced in the first place and they would be a prime target for thieves and artifact hunters. The one in the article could easily be the last one remaining.
Would the maker have really been thinking that the thing being made would still be usefull 50, 100 or 1000 years later? Sure, it could be used to look that far ahead, but would they have been concerned about longevity of the device itself?
On one hand, it's hard to imagine a craftsperson considering the life of a piece beyond the life of the craftsperson themselves.
But I suspect a craftsperson is first and foremost focused on the quality of materials, quality of the construction — no doubt in large part so that the piece is durable. The degree to which that adds to the longevity is probably unimportant.
Like arguing wether the workbench you built will last 200 years or 400. What does it matter and who could know?
