Just to clarify my viewpoint... I buy almost everything used with the intention of selling it fairly soon. My two primary commuters have been around the longest, because they're enjoyable and almost right.
I guess I'm going on the assumption that most people won't buy the right bike the first time. Knowing that you'll lose less money (or ideally no money if you bought it used) will make someone much more likely to sell it and get something they will hopefully be happier with.
It's not about being collectible, it's about people not wanting to pay money for a used bike they consider to be lower quality.
--------
I guess you can't have anything too nice or risk being laughed off the polo court right...