Because Riot doesn't know how to creative-write without misusing fancy vocabs in wordy phrases. Subsequently, this style is established as the vernacular of Valoran.
I would like smaller titles, like "XXXX, The Destroyer", is shorter, a bit less creative, but have more power behind it that a long awkward tittle like "Renekton, The Butcher of the Sands".
© 2013 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.