Here is the thing, if you have a nice nexus tablet or a larger phone, and you laying down in bed, snuggling with your e-book, why do you need the screen to rotate and make your page have longer lines? almost any reader I know prefers reading in shorter length of line. it is faster and your eye gets tired less and you concentrate more.
you might say, Dude just turn off the auto rotate. but NO ! I totally want to watch my youtube videos in in a rotated mode. or my navigation is so much nicer when it is rotated.
Auto rotate should be smarter, to differentiate if you are reading something or watching something.