Mark Liberman has a great posting on g-dropping in the US presidential debates (link). Mr Verb has a related post, too (link).

You've gotta be pretty familiar with g-droppings when you're trackin' the elusive Alaskan G. Me, I just prefer shootin' 'em from a plane.

I hear what Liberman is saying, but it must be instinctual and not political. No one thinks about each and every word he's saying, especially in a nationwide debate. As one who saw the whole debate, I hadn't noticed it.

I noticed in one of the Mr. Verb links, the good old "Language Monitor" is quoted again. Apparently during the last debate, McCain spoke at a 7.4 grade level, while Obama spoke at a 9.3 level. However, Obama's falling, according to this "esteemed" journal, was that he used the passive voice twice as much as McCain. Audiences, according to the "Language Monitor," respond better to the active voice because it's "more direct."

Motivated Grammar talks about the GLM analysis.