The problem isn't that they borrow ideas from others; it's that they do it in such volume and with such little creativity of their own. Zynga faced similar criticism:
They really drive home a few points often overlooked:
Business fundamentals are really important, while not the only thing, that are a critical aspect of longevity.
Ideas are less important than execution.
Porter's 5 forces model provides some basic criteria for evaluating competition. If you provide something easy to copy and the barriers to entry are low, it could be a good idea but not a great business. In one of Sam Altman's lectures the "when to expand internationally" question is brought up. I don't want to misqoute it, so I won't. The context might have been the Samwer bros, but he gives some good insight.
Again an italian restaurant opening up on the blog right next to another isn't going to complain that someone steals their idea even though they sell more or less the same products.
Furthermore Rocket Internet takes ideas that haven't yet come to Europe. People do that all the time just very few have been so successful as the Samwer Brothers.
The "ideas don't matter" bit is to help people understand that having one idea that feels smart does not guarantee them success. It is not some eternal, fundamental truth.
Opening up an Italian restaurant right next to another doesn't matter because it's the eight zillionth Italian restaurant in the world and the concept was jointly created over centuries by the nation of Italy and many entrepreneurs.
Moreover, even when similar restaurants open in the same area, they typically work hard to distinguish themselves. If somebody opens up a restaurant and copies the exact menu, layout, decor, trade dress, pricing structure, and dish names, that still looks shitty.
I agree that the Samwer brothers are unusually successful copycats. But as with other parasites, I don't think that makes them better; I think it makes them worse. I can forgive it when it's some desperate, low-rent operation, like somebody selling cheap DVD copies on the streetcorner. But these guys clearly can afford to innovate; they're just happy exploiting the work of others.
http://www.forbes.com/sites/insertcoin/2012/08/08/a-photo-re...
Both companies do of course make money. But that doesn't entitle them to respect, just money.