Interesting exercise. When politicians write at a "higher" level of literacy, they are often accused of being "elitist," "over-educated" and "out of touch." Good writers know that if you want to be appreciated by an audience, then you write for that audiience. Both presidents and their speechwriters know that not only is there a "sweet spot" for speeches, but that there are passages which are lofty and passages that are more commonplace.

I'd be interested in comparing the results with more than one sample of writing per president.