It's probably more than that - it may have something to do with the fact that politics representing class interests have never been institutionalised in the US. To illustrate that point, US was one of the first countries to implement a quite generous social welfare program in the end of the 19th century, but the justification for that program was compensation for real and imaginary losses sustained by families during the Civil War - or "protecting soldiers and mothers" as Theda Skocpol put it, rather than "protecting workers" as in Western Europe. Skocpol attributes that underdevelopment of class politics in the US to the universal MALE suffrage - which superficially united men of all classes, thus blurring class divisions and interests.
Whatever the explanation, the bottom line is that if you do not have a class-based politics (i.e. the political representation of class interests), politics becomes an empty show of personalities, celebrities, and verbiage. Ironically, the US and the x-USSR & satellites have something in common in this respect.
wojtek