I'd personally like to see this, since I've been playing since the days of pre-online store and of course pre-buyable character slots. As such, I have two accounts, both of which have all three campaigns on them. I would have liked, back in the day, to have been able to buy simply more character slots, and I would very much like the ability to merge the accounts, even now, or move characters over.
Of course, as it has been stated, more accounts means more money for Anet, so they're not quite so likely to do this now. But at the same time, it's kind of past the point where they ought to be too worried about that in the first place.
As for ebay, they police ebay quite effectively, last I heard. I don't think that it would lead to an advance in that market of any sort. And there will always be people who try to do that anyway, regardless of everything else.
Personally I think it's a good idea to have characters transferrable or accounts able to be merged. You've got my support anyway!
