Most standardized testing in the US, especially the ones deployed at a national scale, are designed for grading first, and testing second. This is a simple concession to feasibility: if you're trying to evaluate a few dozen million students, scantron is the only current tool that is time-efficient, cost-efficient, and consistent ("fair") at scale. The constraints imposed by that tool are significant, and tying so much incentives to those tests have warped the whole education system.
Automated essay grading, no matter how imperfect, would still be an expansion of the available testing techniques that could be deployed at the national scale. It would expand the range of skills that are measurable, and therefore incentivized to teach.
The cynical way of putting that is, no matter how shitty computers are at grading essays, they're still an improvement when the competition is multiple-choice questions. I have decided to be excited by that.