Penguin,
When the body or neck vibrates (due to lack of rigidity), what sets the body or neck in motion to vibrate? The grace of God?
No, it has to steal vibrational energy from the string.
A larger string has the capacity to coerce the body more, and set up these vibrational resonances. Depending on the "tone" of the wood, that's exactly the tonal composition or "signature" that will be "stolen" from the string's vibration. The wood acts like a subtractive filter. A hollow body will vibrate more, and thus more impulse will be "stolen" from the string.
Another thing to realize: higher notes take less energy to produce. A body or neck that is more rigid, will resonate at a higher frequency, and thus steal less total energy from the string. This reduces the involvement (amount of energy transferred back and forth) between the string and body. Yet another reason why guitars are less affected by woods than basses.
Now, to make matters even more complex, energy doesn't just flow from the string to the body...the body gives some of it's energy back...coloring the sound yet some more. In actuality, energy flows back and forth between the body (neck) and string constantly. You can even watch it, if you play in front of a strobe source (like a TV). You can watch the energy swell from the string, to the body, and then back again. You can actually watch all sorts of dynamics - even the nodal points along the string become apparent in front of a stroboscopic background.
Spend less time trying to be such a wiseass, Penguin. I'm only trying to share some knowledge.