It's no different, its a 0% loan. Paying up front with 0% interest doesnt make much financial sense when you can leverage that money elsewhere. Anyone who invests would tell you the same.
For me, I get 5% cash back for utilities on my business credit card with my ATT bill is; Apple is not. So since the phone payment is part of my bill I get 5% off each payment which adds up. About $27-28 off the phone cost of $550 if upgrading yearly (half the $1099). So it's a good chunk of change doing it that way for me versus paying up front.