Why visualization is to be taken carefully

Visualization is a form of art (ok, maybe for those of us who can't really draw, but it's still a form of art!) and as such, there might be some discordance concerning choice of colors, movement, proportions and so many other aspects. As any other form of art, designers can too take critics personally. I hope that either that's not the case for the responsible for the design I'll be talking about here or he/she doesn't read this blog.
Anyway, lets get it started.
Last year, Business Week published a very interesting article on Solar Energy Panels and how the supply and demand theory had and would affect their prices. Along with the article, BW published the following graph:

First of all, this is not a very simple graph to fully understand since the buckets are not well specified. This is sort of covered in the main article, but the graph itself doesn't bring much to the table. Second of all, we can only see the most recent years of concrete data ('07 and '08), which is less than the projection of future prices ('09 to '12). Second of all, not everyone is accustomed to the unit of measure: Dollars per Kg per year. Last, but most significantly, the most important part of the graph - the forecast part - has absolutely no information aggregated to even give us a hint to why that is or to how much the prices will be in '12. We know the price will range from more then $0.00 and less then $100.00 and I can guess that they might range from $25.00 to $50.00, but there is absolutely no reason for the viewer to have to guess that value.
In summary, it's clear that this graph has not been completely thought through. There are a number of ways to depict the information and if you're quite sure how, I personally don't think you should try to get fancy, just use the most common graphs with attractive colors and whatnot. And even if you are used to building graphs and visualizations, it's a good idea to have hallway tests - if you don't know what hallway testing is, you should really read this article by Joel On Software.
I hope I wasn't too hard on my critics, let me know what you think.

Graph seen on Junk Charts

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