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Because Looker needed some character development. He's been around since Gen 4 and hasn't really done much. At the very least, X&Y have elevated his status so the next game you see him your reaction won't be "Oh hey... it's Looker..." but "OH SHIT SON! IT'S LOOKER! What's this motherfucker up to now?"
It would be excellent if the wrote him into the stories of future games. An International Police officer is a good character to tie multiple regions together.