I see where you're coming from, but I actually think that both of these posts describe ways for students to get more open ended assessment, rather than automatically graded multiple choice questions (i.e. what's typical in MOOCs and Scantrons).
If I recall, they had computers grade the GMAT essays for at least 10 years, but they had to have a human in the loop because that is the ultimate measure for whether a computer is "correct" in terms of grading an essay.
The automated essay grading stuff typically looks at writing style more than content, but it's true that it's a problem that tons of people have worked on and there's been some cool progress there as well. We're not really working on bringing AI to essay grading ourselves though.