The iPhone used to be exciting and interesting. It used to be aspirational and high-end. Now the world and his dog has an Apple handset and it's turned from something special into a poor substitute for one of the countless alternatives... The iPhone is run of the mill. It is predictable. It's just plain boring.
The logic behind Project Ara is pretty solid when you consider how fragile the current crop of smartphones are. A poll by MobileInsurance.co.uk last year suggests that 25% of iPhone owners continue to use their device with a broken screen, reasoning that they couldn't afford to replace it or were unable to easily repair it.