While the iPad can do many things, it is missing the ability to be controlled by anything other than a finger. This can be frustrating if you would like to use your iPad for more intricate activities such as drawing or designing.
Fingertip input is great for most touchscreen usage like typing, web-browsing - all sorts of virtual button-pushing tasks. But for many people, drawing remains an activity best approached with a pen, pencil, brush, etc.
With a bit of conductive foam and wire, it's surprisingly easy to make your own conductive stylus, suitable for use with iPhone, iPad and similar conductive touchscreen devices - and you'll likely find it a lot more precise compared to regular fingertip input.