One of the instructors at my UBI class last week was formerly a product manager for Giant. He explained that when manufacturers are choosing parts to meet a price point on a particular bike model, they will often go with a respected rear derailleur (ie. Ultegra) and a cheaper front derailleur and crankset. This is because the average customer will see the rear derailleur and think of the bike as coming with Ultegra, ie. it sells as if it were full Ultegra. A savvy mechanic or well-informed customer knows that the bike would run better if it had an Ultegra crankset and FD and a cheaper RD. But such are the vagaries of the marketplace.