It's not the honey that produces the nutrient.

The nutrient comes from a plant and climate change is probably altering plant biology to make this nutrient harder to come by. Not to mention the supplemental feed given to bees late fall through early spring (a period where honey harvests have ceased) probably lacked that nutrient.

So, not harvesting honey wouldn't be the answer. Honey bees have been apart of the agricultural process for thousands of years (honey was harvested as far back as ancient Egypt and was used in the mummification process). So, if we stopped honey harvesting, it would be detrimental to both bees and the agricultural system.