Why bother to observe the Moon? The answer to that is likely to be different for different people. It is seeing the stunning vistas of an alien world that drives me. What about drawing the lunar surface, though? It is a lot more trouble doing that than passively looking through the telescope eyepiece. Also, the day of the amateur lunar cartographer is now long past. Thanks mainly to Moon-orbiting spacecraft, the various lunar features have now been mapped with much greater precision than can possibly be achieved by an amateur's eye, telescope and pencil.
So, why draw the Moon? The mountain climber's adage “because it is there” might suffice as a reason. The Moon's beautiful orb is every bit as much a part of nature as the mountains and valleys, fauna and flora here on the Earth. Drawing the Moon's surface details is also a powerful way of communing with it. The process of doing so will also create a kinship between you and the selenographers of yesteryear who had to draw the Moon because there was no more sensitive way of doing it. You will certainly get to know the parts of the Moon you sketch with great intimacy. You might never get to travel to the Moon but carefully observing it through your telescope and drawing what you see through the eyepiece surely comes as a good second-best. So, if you decide to take up lunar drawing, do so because you enjoy it.