I personally think it's distasteful to rip off a website design directly, but if they can launch a proven business model in Europe quicker than the American originators (or because the American company can't/won't go international), why not? Imitation is the greatest form of flattery and all that.
I'm not sure I understand why it is so bad. Yes, it is in bad taste, and yes it is wrong to copy layouts (probably illegal to copy layouts). But copying the business model itself? what is wrong with that, especially when the 'original' companies they are copying from, are not operating in Germany (and other countries the samwers are expanding to)?
Well, with the arrival of Project A ventures, you may not have to worry about getting them outlawed - now that an alternative exists you will probably have more people siding to the route of original ideas anyway.
As an American living in Berlin for the time being, I find it remarkable how often the Samwer brothers are cursed by startup founders. But, I agree: invent your own businesses :)