bright, shiny objects

One of mankind's primary drives, falling just below food, water, and sex. Our fascination with things like gold, silver, and gemstones comes from this. Diamonds are especially notable for this because they are indistinguishable from most other clear, facetted rocks (like quartz) except for an unusually high index of refraction, which makes them extra sparkly.

See also: bright, flickering images

I believe there is merit to your argument. However, for a long time gold and silver have been known for their wide and varied industrial uses. I believe that gold is one of the most ductile and malleable materials in existence, for example, as well as an excellent electrical conductor.

However, long ago people didn't know this and liked to make jewelry from bright, shiny objects because they reflected the sun in interesting patterns that were aesthetically pleasing to look at. Perhaps, it would be more accurate to say that aesthetics are one of mankind's primary drives, not merely a rat-like love of shiny things.