To the first point, motorcycle sales in the US never really recovered from the recession, and it doesn't seem like they're coming back anytime soon. Is this because new motorcycles (regardless of brand) cost more than they used to, a lack of disposable income among the target audience, or failure of motorcycle manufactures to branch out to new audiences? I don't have the answers to these questions, but I think that they all play a role into the sales decline.
Secondly (and more specific to Harley), the used motorcycle market is HUGE. Go on Craigslist and look at the motorcycles that are on sale. Near me, it seems that every 3rd or 4th bike is a Harley. When the used market is so large and the models don't change that much from year to year, why would you buy new when you could pick up a slightly used bike and save 10% to 20% off of the sticker price?