Angela Merkel made a statement about the decision. All I have to say is, "At least she's honest." She said, "If the euro fails, then Europe fails. If we succeed, Europe will be stronger." Yes, Germany, if you do succeed, Europe will be stronger. However, there's no reason to go about this like a lone gunslinger. Understandably, some countries (Read: Greece, Spain) have shown that their contributions to the crisis will not be positive ones. Thus, I could see why Germany might be fed up with its fellow nations. The Greece bailout took a lot of bickering to get passed until Germany finally decided to give in.
The plan to ban short selling may backfire, unfortunately. Other nations, notably France, openly showed their disappointment not necessarily at the decision, but at the choice not to inform other countries of the plan. Markets in Europe were down at least a couple percentage points, and the euro lost around a cent to the dollar. It seems the backfire has already begun, let's see if the end results are better then the current ones.