1. They are there so you can have a sketch first before you go over the finished project. 2. You have them so you can have a more realistic sketch for people to build off of. It just makes the sketch more understandable. 3. 4. 5.When you have multiple drawings you can see it from many angles and you have a better chance of building it in a realistic way. Rather if you just have one drawing you can't have the depth of an object or your going to lose all the angles that you need to build.