The Kindle was originally designed with no 'on/off' switch because the way it functions there really is no state of on or off. The product mgr (I believe Jay Maine?) was concerned about being inundated with customer calls asking how to turn it off so the soft reset capability was renamed on/off and changed from momentary to static so that there would be the appearance of an on/off capability.
I have never had an FA or anyone else ask me to turn my Kindle off during TO or Landing. Pilots seem to be aware of how Kindles function and most don't seem to have a problem with people using them (with wireless off) during TO/Landing.