But the point is that by making the stage re-usable, you significantly cut your cost/kg, meaning that even with a decreased capacity it's more cost effective, as you could do several launches rather than just one to lift whatever.
Of course, also bear in mind that this isn't technology just for the Falcon 9 - this is the test-bed. Once we have the systems in place for a reusable first stage, this can be applied to the heavy (which of course uses falcon 9's), and other future generations of craft.
Until we've got SSTO spaceplanes or space elevators, this is pretty much as good as it gets.
Of course, also bear in mind that this isn't technology just for the Falcon 9 - this is the test-bed. Once we have the systems in place for a reusable first stage, this can be applied to the heavy (which of course uses falcon 9's), and other future generations of craft.
Until we've got SSTO spaceplanes or space elevators, this is pretty much as good as it gets.