Why Does the Affordable Care Act Discourage People From Buying Health Insurance?

I read the Yahoo article, Millions Trapped in Health-Law Coverage Gap, and was reminded of one my pet peeves with the Affordable Care Act. Why does the ACA push people into Medicaid if they want to buy subsidized health insurance on the exchange? If someone whose income is less than the Federal Poverty Limit wants to buy health insurance rather than receiving “free” Medicaid, it sounds like they think they belong in the middle class, their income problem is temporary, and they are taking personal responsibility for their health. This is the type of behavior health care reform should be encouraging rather discouraging.