Magnetism and power is generated when there is movement and fluid magma circulating in the middle of a planet. The moon is bone dry.
A pale of wet sand is much heavier than a pale of dry sand. Without moisture or an atmosphere and with much of the moons crust containing Titanium and other metals from billions of years of bombardment of space debris this makes for a hard solid surface. When a comet hits earth it smacks into the moist and weak soil making a much more disruptive impact that can echo and reverberate through the crust and cause earthquakes and crustal shifts all because of the softer materials and differing makeup throughout earths crust. The lunar surface on the other hand is dry and solid and without shifting fissures all the way around, covered in asteroid and comet dust that is made of mostly metal elements. No wonder the moon rings with impact, theres no differentiation between techtonics to absorb the shaking so it circles around the whole globe repeatedly with little decay, just like a bell, because essentially these are the same properties as a bell.
What about the craters being flat and circular why dont we see other kinds of scarring? These questions are also easily answered with the same data that the dry Titanium filled surface is too hard and without moisture or plasma to weaken it, therefore when an object hits the moon it explodes violently. Theres no soil to give way, just metal rock. These impacts melt the crater floor and the insides of the crater rims and when the lava cools you get a smooth flat bottom. On earth the comet can burrow deep and displace more mass with less resistance. As for there not being visible gouges on the lunar surface at more noticeable angles, same thing. The surface is so hard and dry that a high speed object would simply explode at pretty much all angles. Theres nothing soft on the surface except for fine dust, dust made of the same dry rocky metal elements. While that makes for a very undiverse scarring of the lunar surface, 2/3