With mobile computing, speed is essential
Very essential. Digital camera files are getting bigger all the time and you don't always have the time or place to set everything down and wait for the camera to transfer its files to your laptop/tablet or even swap memory cards. Data transfers between portable drives and desktops or even external drives take longer each day. That speed is critical for a person on the go.
Too fast? Ask that question again in 2 years--5 years. You're going to wonder how you ever put up with that belly-crawling USB snail.