As designers, we must be able to daw out and plan our rooms and spaces to scale. You need this skill whether or not you are also going to use CAD. You need to know how to check measurements on site and in clients' homes. If you are designing any space, be it yours or someone else's, you need to make sure your furniture fits and that you use the space well. You can only see how the space is used by drawing everything out and space planning. You will need to know how to draw up elevations, to add design detailing to rooms such as kitchen and bathrooms.
If you are still unsure, give us a call and we can answer your questions and talk though your options.