If washing your hands takes 2 liters of water, isn't that an environmental problem if it could be done using just 1/10th that amount?
Perhaps, but is that a problem? If that amount of water costs $100: probably. If that amount of water costs $0.01: probably not.
I know so-called externalities can blur the picture, but in general the cost of things reflects how much effort was needed to produce them. So if Bitcoin mining is profitable, that probably means a produced Bitcoin is worth more than the effort it took to produce the required energy. No doubt Bitcoin market developments, and efficiency improvements (FPGA / ASICs) will change the actual numbers here.
Problem much, why? There are so many human activities that require energy, and (often) don't produce results that would be considered useful or valueable. So if you spend (for example) $10 worth of energy to find (is that the correct description?) $100 worth of Bitcoins, you could have spent that energy worse.
Btw: article would do good to report how many/what worth of Bitcoins were mined using the stated amount of energy.