Because "Horton Hears a Dalek Shouting 'Exterminate!'" just didn't roll off the tongue well enough.

... but maybe that's just me. I'm still trying to Seuss this one out, really. - Matty Malaprop

I can see all the best-selling titles now: "King Learax," "A Midsummer Night's Grinch," "Othello, the Places You'll Go," "Yorick the Turtle and Other Stories," "Fox in Saxony..." the possibilities are limitless! - Matty Malaprop