Note that you probably don't need the DVD ("full") image. Most users should use the "minimal" netinstall CD and download packages at install time.
Agreed, but for laptops it’s nice to keep a copy of the DVD iso on disk and in your apt sources so that you can install stuff offline.
I downloaded both because I intend to seed, but yes, if you have a fast internet connection then minimal is perfect... but if you are on a crappy third-world connection where it might take all day to get the image, it's nice to have it all in place when you are ready to install.