I suppose it's because they are not fighting preconceived (and ingrained over almost a decade) notions of what hit-points are.
No. That's precisely the point I wanted to make - that veterens aren't fighting against preconcieved and ingrained notions of what hit points are. They are fighting against preconcieved and ingrained notions of what PnP role-playing is like.
Fourth edition is in many ways nothing like what they are used to from a PnP combat system. Keep in mind that for most of us D&D was at the very far end of the spectrum of realism vs. playability, and not on the realism end. D&D was already about as far along the 'damage is represented abstractly' spectrum as we'd ever played in a PnP game, and when we talked about the deficiencies in D&D compared to other systems it was never 'D&D uses to concrete of a mechanism for representing wounds'. In fact, D&D's use of an almost purely abstract system for representing wounds was the subject of much humorous ancedotes and jokes - sometimes given goodnaturedly and sometimes very much not.
As a result, veterens grope around trying to explain to people what's wrong with getting even more abstract in terms that they hope are understood. So they say things like 'too video gamey' or 'too manga', even those these aren't really good analogies. What they mean is really something like, "D&D was already the game system I turned to when I wanted abstract damage systems and really it was at the far end of what I could tolerate. Fourth edition went more uber with the abstractness, and that's more than I at least can tolerate."
So when someone comes along and says, "Some people are so exasperating for not understanding that hit points are abstract." and seem to imply that the reason people don't like the new hit point model is pure ignorance, frankly, they come across to me as.... well... telling you what I really think of comments like that would violate the policy at EnWorld against personal comments. Suffice to say that I think that they are far wrong on the matter, that such comments are laughable in the light of the 1st edition DMG, and would be advised to ask more questions about and make fewer statements of other peoples opinions.
And frankly, that goes for mischaracterization and exagerration by the WotC developers as well.
We went through all of this prior to 4e coming out at great length. I don't imagine anyone's opinion is going to change now. I tried to like 4e. I set down to think about creating a dungeon for 4e. I couldn't manage to get excited enough about it to put in the work. I haven't picked up a 4e book since then, and have a hard time imagining me playing it even casually. It has nothing to do with failing to understand that hit points are abstract.