Various sights have a built-in Ahhh Factor. Kittens for one thing, babies suddenly breaking into a smile are another. And music boxes. You have to be very hard-hearted to resist one of these gently rotating devices, twinkling Stille Nacht, heilige Nacht. Provided the wood carving is delicate enough, the tune will always imply German rather than English lyrics.
Where does a music box's appeal lie? It starts with the idea. As a wind-up mechanism it's obviously related to the clock. Clocks are serious, music boxes not so, although they are not trivial. Not quite swords into plough shares but along those lines.
The music is created by pins on a revolving drum plucking at tuned metal flanges. Since the system is contained in a limited space the flanges are quite short and thus generate high-pitched notes. Normally we find comfort in lower notes; music boxes are the exception.
The tempo is usually lento, also a source of comfort. You can check this on boxes which may be over-driven by winding the key in reverse. A faster tempo tends to sound inappropriate, even disturbing.
Volume is pianissimo if not pianississimo, suitable for a very humane alarm clock. The drum diameter limits the tune’s duration.
A proper music box faces no serious competition from modern-day electronic gizmos attached to plastic dolls, toy Ferraris or greeting cards. Once people may have been impressed, now such devices are seen as merely “clever”. There is no art in them, only technology.
I’ll go out on a limb and say music boxes are genderless in their appeal. Both men and women respond. Surprisingly, they are not directed uniquely towards children.