I am not a fan of the so called conceptual photography in almost any form. Perhaps the maximum I could consider artistic would be an unfocused image, or a fork on a plate.
However, I think the more important element of the Gursky story, is the so called "Anchor effect".
When you step into a rug shop in an oriental bazaar and ask for a price, the seller will invariably begin with a price which seems far too high. However, he has planted his anchor... If he says 1000$, it is unlikely, you would try to bid with 50 cents - more likely with a few hundred $, even though the rug could actually be worth 5 or 10. It has been observed, that people could be influenced by an anchor number, if they have thought of one, even if unrelated to the value of the object they bid for.
This has been used many times in various stock price and art price manipulations. After all, if a stock XYZ was once bid 100$, at 50$ it starts looking like a bargain...
Therefore, if a banal photo by an uninspiring photographer has sold for 4.3 million USD, and someone offered you another one for 10.000 USD, it would seem a steal...
I have nothing against people using their freedom as they please, as long as this does not take my freedom away, hence, I am totally indifferent to this particular photo sale.
In a situation where my sense of value is attributing a price to an object, which is lower than what it sells for, I simply make no bid and live happy all the same.