Corn or blaming any other crop is not the issue. The water usage is the issue, whether it's for farming, drinking, pumping on a golf course, or into the City pool. Corn is the symptom, not the cause. As a farmer you can make more money raising a failed corn crop than other typical crops (wheat, beans, milo, hay, etc.). Corn insurance and subsidies are the highest out of all the typical Kansas crops. Irrigated ground is completely different than the eastern/central Kansas dryland.
Each registered groundwater well has a water appropriation, or what amount of water you can pump/use per year. This appropriation never changes and is set from the initial water right. Your appropriation is based on the calendar year and does not carry over. What incentive does anyone have to conserve water? You use it or lose it. As the water table declines, farmers have wells that could support a decent crop and make them decent profit start to struggle to support more drought tolerant crops (wheat, milo, etc.). To be more profitable, farmers plant "irrigated" corn for insurance, use the crap out of their appropriation, and then get drought subsidies. $$$ You can't blame them for following the system that's in place.
Use it until you lose it. Problem solved.