I can't think of any photographic print that I would consider to be worth $4M + but I might have an opinion on whether I like it or not.
Its difficult when looking at a representation of the world such as in the picture being discussed. We might say that we could have taken it, but then we didn't did we?
Saying that we have something similar, or rejected the opportunity to create something similar, doesn't really have any bearing on it either. Andreas Gursky creates images for the fine art market, which involves a different sensibility to other photographers who don't.
I have no idea of his motives, whether he is truly "expressing his vision" or simply "doing it for the money", but the whole process of working and the environment in which he works is somewhat different.
The record for the highest fee was previously held (briefly) by Cindy Sherman. Untitled #96: Cindy Sherman's $3.9 million photo (Breningstall.com) This is somewhat different, as all her pictures are elaborately staged self-portraits. This is clearly something that others are not able to duplicate in terms of content, though the concept is not a new one.
Whether something like this has more "merit" than the Gursky, is like most things, a matter of opinion. I personally like her work and always have done, but I leave the financial valuation of it to those who want to buy it.
I feel much the same way about the Gursky. Personally, again I like it, which is unusual because his other pictures don't really give me any sense of enjoyment. However, the valuation is to a certain extent irrelevant. I'm not competing with him, and while it would be nice to sell one of my images for the sum mentioned, I'm aware thats never going to happen.
Its not going to happen because I'm not part of that world, nor do I wish to be, and what I'm trying to achieve with my photography, and how I undertake it, is completely and utterly different. I like to think that Gursky would still be producing the same work, whether he gets the "big bucks" or not, but I have no idea whether that is the case, and since he makes so much money from his photography, it must now be impossible for him to know either.
So rather than money "rewarding" art, are we now in the situation where money "creates" art? and many argue that market forces are driving photographers who inhabit the fine art world, to create a certain kind of picture. Whether thats true or not only they can say, but some of the acknowledged greatest works of art in the world, the Cistine Chapel, the Mona Lisa etc. were commissioned work, so I guess the concept of money influencing artistic achievement isn't really anything new.