duncbdunc, thanks for the info about stucco. I didn’t know that. Based on the cost waiting hawk provided about new stucco, the price isn’t that much more than repainting an entire house.
Roof, it really depend on how long you plan to live in your house and how old is the roof. Is it likely that you’ll move out before the roof even have problem? Tile roofs are supposed to last 50+ years. So, if it’s only 20 years old, you still have at least another 30 years before it might give you problem (if it was installed correctly).
Of course a house with 20 years old windows will worthless than a house w/ brand new ones. The price usually reflect it. However, the return on brand new windows is not 100%, so you can’t just subtract the cost of the windows.
If you’re talking about appliances, they can be replaced w/ all brand new appliances for <$1500. 20 year old cabinet (oak if it's your typical tract home from the 90s) should still be very functional today. It might not look fancy as brand new cabinets but again, that's a want vs need. Of course a fully upgraded house will sell more than a unremodeled house. I don't disagree with you that an unremodeled house should be worth less than a fully remodeled one. But not everyone feel a brand new kitchen is needed.