Graffiti doesn't always have to be tags or bubbles or fancy airbrush work, just look at the work of 'Banksy' with his stencils,
but then he was just inspired by french Graffiti work, that was going on in Paris/France throughout the 70's and 80's.
I would imagine the reason it has not had the same publicity is because the vandals have not been caught or found, if they should however no-doubt it would get the same publicity as the youth who plssed on the war memorial.