Why do all/most diapers have so much color/ink/characters on them?

I don't really understand the point of all the characters and ink in diapers... I would ume it would cost the manufacturers far more money to produce m millions of diapers with so much ink involved.... wouldn't it save everyone a lot more money if they were just plain white? Not to mention the negative affect on the environment all the ink has and moreso how much safer and hypo-allergenic they would be towards our little kiddie's if they were just plain. Were diapers ever plain? Or did they always have characters? I use luvs because there is just that one strip of color across the front and that's it.... anyhow - just wondered.