A few points that might help clarify things for you:
If listed before built, it is not unusual for new construction to have longer days on market. It is difficult to sell something that buyers cannot see. That is in general terms. But my own experience with new construction is that it is difficult to sell before it is built. But the days on market are counted from when iti s listed, not built.
New construction does generally sell at a premium to resale homes. However, a 5 to 10 year old home that has been properly maintained is still a very new home relative to the average home listed. If the home is clean, well maiintained and most importantly, properly priced to the market, it will be an easier sell than homes that are not.
Hard to tell what will happen in 10 years. Prices of real estate most likely will be higher than where they are now, but yes, it will be a 10 year old house then. Today is 2012. What do buyers think of a house built in 2002? They generally aren't terribly concerned about the systems at that point, not that old.
Appliances for a 10 year old house? We're only talking about perhaps a $5,000 difference. It "all depends", a famous phrase. Are we talking a $200k house, $300k or $400. .