To start, a higher octane will run better, based off it's octane alone. Do you need it? Not necessarily, but if a computer has been programmed to 87, 89 will run better. Plus, higher octanes have more detergents and additives to help keep them cleaner, and burn better/clean engine components better. (some people will call this a myth, but the petroleum companies advertise it as such, and false advertising IS still illegal).
Do you need it? No
Is it better for your engine? Yes
Can you run 87 and be just fine? Yes(even the petroleum companies, at least Mobil, tell you to only run what you need)