Sorry, but I'm with Karajorma here in one main factor. America (and China) has a vast population, therefore it can produce a lot more competitors than other smaller countries, and so therefore stands a higher chance statistically of getting more medals, and can produce world-class competitors for a lot more disciplines.
That's why I prefer the points system (or even the population per medal one), so that quality has an impact as well as sheer volume.
That's not knocking the US' achievements, individually, those athletes did great to get bronzes and silvers, I couldn't have done it, but Kara's right, to the athlete there is a world of difference between third place and first place, and the medal system should reflect that to a degree.
I don't doubt we will have our own set of controversies and claims/counter-claims when it comes here in 4 years though.