To the OP:
I believe so, the wood relaxes under years of string tension and playing.
The treatment of wood referred to earlier is known as acrylisation, acrylic resin is injected into wood under pressure. Probably makes the wood denser, more consistent in tonal response and lowers the resonancy peak of the wood (less risk of deadspots).
Not sure about factors relating to wood drying out, wood absorbs and emits moisture all the time, depending on the surrounding humidity. Not sure about Fender opting for lighter or heavier bodies either, as far as I've been able to tell they didn't care about the wood density, the place was a production line.