I suppose one could also make the "day" shorter or longer with relative ease by reducing or increasing the number of healing surges across the board. I will admit that I will still have to see it in action to see if its default setting is right for the group I play in.
As for the whole unrealistic healing to full hit points after an extended rest, the only thing I can say is that since hit points are now finally being described up front as the abstraction they've always been, when you regain your HP only a fraction of that is actual physical wounds healing. Also, at least for me, situations where your character's guts are sprayed out all over the dungeon floor are situations where that character is dead.
But then again, as each game is different, and HP means something different for each one as well, how magical or supernatural the healing over an extended rest is is left up to the individual DM and group. I suppose if it really matters, you could institute some form of restriction on how much you heal per extended rest, maybe even change it to something where a character only heals a certain number of hitpoints (equal to their healing surge?) per hour of complete rest or somesuch.
I just know that for me the complete heal after an extended rest means only a small amount of healing wounds and many more things such as recovering from exhaustion, recuperating from the mental stress of battle and conflict, and perhaps the most important, the light of a new day.
EDIT: Whoops, missed neceros' post, still stand by my view though...