The vehicle is far lighter when it's time to land it than it is when it's launched, since most of the fuel has been used, so it's not "half" - more like 30%. But if you can launch 140% of your original throw weight in two launches by simply refitting and refueling between them, when fuel is 0.3% of the cost of the rocket, instead of building a brand new rocket for the other 40%, then you're far, far ahead of the curve. We don't throw away 747's after every flight, and a rocket costs about as much.
Good Luck with that marketing.....