[ffcmike]

The idea behind it is that you're going into the bed to take a rest (what a bed is for).
Entering the bed, immediately saving and then exiting the bed bypasses this.
I understand that not everything has to make perfect sense in a game but if we were going to make it instant it might aswell be a button click or possible for when sitting on a chair.

There could also be a scenario in future where there could be a series of quest levels containing beds and that it might be a good thing that players can weigh up whether they would want to spend that extra 15 seconds for assurance or waste no time and take that risk.