I understand the sentiment to treat hps more as an abstract pacing mechanic and not think too much about what they really represent. But if the continued arguments over warlord healing are any indication, for a big chunk of people it really *is* important and I believe it's an issue they're going to have to address. Indeed, I think it's one of those issues right at the heart of the gamism vs simulationism debate. Personally, I think it's okay to come up with rules from a gamist perspective but those rules have to be followed up with a discussion on what those rules means (or can mean) in the imagined space of the game world.
I mean, if hitpoints are not purely physical, then what happens when you take damage? What happens if you take damage that is physical but then "heal" it via non-magical inspiration? Lots of non-4e people might roll their eyes at the ability to do the latter (again, the warlord healing argument). So while you can just wave your hand and say it doesn't matter, I think as a game designer you need to have an answer for those people.
I find this odd as an argument as the last twenty years of video RPGs do not have much to say on this issue and have no troubles in going from an initial value of 100 hp at level 1 to something that is usually measured in thousands of hit points by the end levels of the games.
One of the most interesting things I read recently was on dogs playing. When a dog nips at another dog it not only signals to the one dog that it 'tagged' the other dog but it also signals that the two dogs are friends and playing together because there is no attempt to 'hurt' the other dog and draw blood.
DnD in no way really attempts to calculate the odds of an arrow shot but an elven warrior striking an ogre in a stiff breeze from 200 yards and the effect of that attack is lying to themselves. Even some detailed versions of Twilight 2000 are still well short of 'reality'.
You can make a more 'realistic' represenation and there are games like 1e/2e Runequest which take into consideration types of weapons, armour, area of body hit, blood loss. The Riddle of Steel is supposed to be very good for this level of detail but DnD has never tried to be more then a game when it comes to combat. The usage of hit points is purely game design.