I grant you that finding foodplants and mates for moths flying at night is almost exclusively done using chemical cues. For instance, there is some documentation for the movement of moths out of the west coast lowlands of Costa Rica during the dry season up into the moister mountainous areas to the east, and back down into the coastal dry forest during the rainy season. The observation that moths fly more strongly on humid, cloudy nights is also well documented, but to say that it doesn't make much sense therefore that they would use lights as a navigational cue doesn't necessarily follow. Unencumbered pigeons do just fine on a cloudy day as well. However, release a pigeon with a magnet on its head on a cloudy day and they fly around aimlessly.
Noctuid moths migrate using the moon as a primary reference point.
To calibrate the location in the sky with actual geographical direction, they periodically use an internal geomagnetic compass. On moonless nights they navigate solely with the geomagnetic compass. I guess using the moon is 'easier', and therefore they 'prefer' that when it is visible, hence the screwup when bright lights are visible. I know this has come up in discussions with other entomologists before, but I am unaware if this is actually scientifically documented. I agree that this may be a possibility, but there are three things which suggest that this is certainly not the only, or even an important, mechanism.