You are absolutely right if one is using today's rocket paradigm.

I think that our basic difference is that we are talking about different time frames. NASA's stated goal is to reduce launch costs by one order of magnitude by 2015 and by two orders of magnitude by 2040. I think they have a 50-50 chance of achieving that reduction by that date. I do think that such a reduction can be achieved by 2060 (or so). So I am really talking about the mid 21st century, when I believe an explosion of space exploration will be possible.

I think you are concerned about when the first mission to Mars will take place. It may well occur long before the time frame I am talking about. In such a case the costs will be enormous and the returns (to the average citizen) minimal. Such a Mars program will then suffer the same fate as the Apollo program. The average citizen will see no return for a huge investment and the program will be canceled, even if successful landings have been achieved. Such an outcome will likely once again sour the public on space projects in general. I think the ISS is headed in this direction also. I for one would not want this to happen, and am willing to forgo a Mars mission in the first half of the century to avoid such a result.

Achieving launch reductions of the magnitude suggested will require totally new approaches to and thinking about launching. These same changes in paradigm will likely apply to interplanetary travel as well. Several possible alternate systems are now being researched both for launch and interplanetary travel: Tethers, Lightcraft, Sails, M2P2, and others. If even one of these pans out and can be developed into a practical system the old method of calculating fuel requirements becomes irrelevant.

I would advocate not worrying so much about when and how the first mission to Mars will occur. Instead we should be concerned more with developing our technology so as to reduce the costs of space access. Don't spend 50 billion on a Mars mission. Spend 20 billion on developing launch technology. We then may get to Mars sooner and cheaper.