Art is made to evoke emotion. (or dispose of it) Graphic design is used for the same purpose. Designers working to promote, whatever it is that they representing, have to strategically plan a way to pull the viewer in. The greatest difference from this aspect would be that art... fine art is usually created from within. An artist can take a thought, viewpoint, or happening and interpret it. Most of the time this happens without direct direction from a client saying... "I want this and it must be like that." Designers are cot completely stripped of their creative cove but it does seem to be a bit more demanding. Does this make it any less of art form? Not in my opinion.
When it comes to the tools used, I don't believe that should be a consideration. There are many mediums in art. Those of us who have sat and "made love" to our machines hours on end know this. Working digitally takes talent as well. All the same rules apply. Personally, I get more gratification out of a piece of charcoal than a mouse or pen tablet. That does not change the effort and thought that goes into a well produced digital illustration or design. Hey, design has not always been the product of a machine and there are still some who like to rock it "old-school."
When it comes down to it, there are tons of design pieces in some of the greatest art museums today. Someone considers this stuff art. It is part of our culture and history. Most of these great designers were not just Graphic Designers- they were painters, sculptors, and photographers.
My 2cents: Graphic Design becomes art through the artists that carry a passion for what they do.