I bought the first one - but only because I'm a trophy whore & missed the one for killing a guard while flying the glider (was the only one I needed for the platinum, and I couldn't be bothered playing through two thirds of the main game again just to get back to that point!!).
TBH, I don't buy this whole 'It should have been included in the game' argument - the game didn't suffer in any way without it. I haven't heard the same level of moaning about Fallout 3 that had a wholely unsatisfying ending, that was only rectified by DLC.