I think they're there to be cinematic rather than difficult/easy. I generally don't like QTEs, but the sight of Starkiller tearing apart that AT-ST was pretty awe-inspiring. A lot of other QTEs are similarly spectacular, like those found in Conan and Viking: Battle for Asgard where you use them to slaughter massive beasts or giants.
I think it can get a little weird in a game like The Force Unleashed where you have all this freedom in deciding how to dispatch your enemies until you get to a boss. But I should also say, while I know a lot of people disliked the demo, I had been starting to doubt the game and it put TFU back on my must buy list.