How does gold's "technical and aesthetic value" make it undervalued?

Technically, it's useful for corrosion-resistant connectors, both as a plating and as the thin wires inside chips which connect silicon to the outside world. Those are the only major technical uses I'm aware of.

Aesthetically it's still good. However there's been a massive drop recently in gold jewellery sales, as white/grey metals (platinum, rhodium and titanium) are out-selling gold. Dentistry has long since abandoned gold as its metal of choice; gold teeth should properly be regarded as jewellery too.

In other words, only the "tradeable" aspect of gold is really keeping its value high.

And I'm not sure what your argument is. First off you say that we need a means of exchange because barter doesn't work, but then you lauch into an attack on fiat money. The point with any currency is that so long as you're spending it, it doesn't matter how many dollars, pounds, Euros or stones-with-holes-in it takes to buy something, the relative values of two items remain the same. When I was in Italy as a kid, a loaf of bread was 1000 lira, but a car would cost you 20 million lira. Back in Britain, a loaf of bread would cost you 50p and a car would cost you £10,000. The numbers don't matter, because the value of the means of exchance in relation to everything else remains constant. The fact that the dollar numbers are different to what they were in 1967 is immaterial.

Graham.