Thanks for A2A and asking a beautiful question.
While considering exaltation and debilitation, one should consider the nature of the planet and nature of the zodiac sign.
Moon is the Mother. It is also that SIGNIFICATOR of the mind.
Now it is exalted in Taurus, which is the most stable of all zodiac signs (fixed earth sign).
Moon, by nature is nervous and fickle and prefers the stability that Taurus provides. A moon in Taurus gives you a strong and comfortable mindset and you get what you call an extremely stable mind.
On the other hand Scorpio is the sign of EXTREMES, which swings from one extreme to another. A moon in Scorpio brings you AN UNSTABLE mind, which tends to go from very happy to very anxious in a matter of seconds. Moon hates that kind of swings. After who wants an UNSTABLE MIND.
Moreover, Moon being the mother, likes to be in Taurus as Taurus is the sign of warm house, possessions, and luxury. A mother likes a place where there is a warm kitchen, all good things and comfortable luxurious surroundings.
Whereas SCORPIO IS THE SIGN OF THE UNDERWORLD. A mother is never going to be happy in a gangland.
Hope that explains.