Will Wright says player stories will always be more powerful than scripted stories. The popularity of The Sims, Leeroy Jenkins, and machinima all prove this.
Then again, scripted stories flatten the learning curve for creating player stories. Grand Theft Auto San Andreas proves that compelling scripted stories and complex player sandboxes are not mutually exclusive.
Seems Rockstar will continue to combine the two with Grand Theft Auto Vice City Stories. The trailer really packs a Hollywood-style emotional punch.