China is the largest market for BMW (yes, BMW sold more cars in China than in the US since 2009) , and they have been making BMW's in China for years. Frankly I don't think this is a wrong move because this venture is made to mainly serve the Chinese market, this business model have been successful pioneered by VW and Toyota, and to a smaller scale, Ford. We don't have to buy these cars but that venture is still going to make boat load of cash for them.
Image from Car&Driver