Traillers are meant to make you want to watch the show. A fast and pacy trailler can make even the dullest programme look flash and worth watching. It's all done to sell the programme to you the viewer, although if you hate the trailler then you'll probably hate the show.
I do agree that the never ending moving camera can be very annoying. Remember when Jamie Oliver first appeared on the BBC with the camera swooping all over the food, never got a really good look at any of it. TV people loved the effect and still do some six years later.