Papa, not necessarily true. Most skis are designed for about 100 days on snow. For the average skier, that is about 10 years (most consumers ski about 10 times a year). Now another thing is that foam core skis tend to breakdown after time if not maintained 100% properly, which can lead to a concave/convex base (the ski rides on the edges, or rides on the base with the edges lifted off the snow). Yes, this can be prevented by properly maintaining wax levels (making sure they are always waxed) and especially by putting a nice heavy coat of wax, and not scrapping, on the ski before putting them away (off-season). Typically, most skiers will feel like a foam ski is a softer flex (granted different top/bottom sheets can affect this), this is often because there is nothing structually in the core to make up the camber of the ski. Basically once the ski loses its camber its shot, its not going to ski properly anymore. A wood core ski typically will hold its camber better than a foam core ski, and is not as succeptible to core breakdown. Typically, skiers will feel like a wood core ski is 'stiffer' or has more snap, because of the (as you said) linear cell structure of wood, it will try to push itself back into the shape it was designed (try to push the tip and tail back, creating the camber).
Now to look a little deeper into the core, you can have a couple different types of wood core. Most are steamed and bent to create the camber. The problem is that this will, over time, 'breakdown' and bend back into a flat piece of wood (camber breakdown). But, some manufacturers actually cut the camber of the ski, instead of bending it, meaning its natural shape is the skis production camber. This will take a longer times to breakdown, since the ski actually has to bend out of its natural state to become a flat piece of wood.
Hopefully this explains a little bit, but the most important thing is what the skier is looking for, personally, I try to stay away from foam core skis, but I would never decide between skis strictly based on core material.