It's a hell of a lot less dumb than growing crops for biofuel on it, to start. And it's not even an either/or situation, you can do both on the same piece of land. I think there is plenty of 'arable' land for which the most productive thing it could be doing is solar power.
Agreed. I'm very pro-solar but there should be incentives for residential solar and solar on commercial buildings first. Covering up farmland and natural environments should be a last resort.
Yes, but the reason we incentivized ethanol production is to not lose the productive capacity for corn in case we need it to feed people. Having a significant excess of food production capability is incredibly important to long term stability. You really can't overstate the importance of food production capacity.