Perennializing crops

An academic recently forwarded me this hypothetical "50-year farm bill." It claims that perennializing crops will provide substantial benefits, and we should therefore devote substantial research attention to developing perennial versions of crops like wheat and corn.

"Perennialization of the 70 percent of cropland now growing grains has potential to extend the productive life of our soils from the current tens or hundreds of years to thousands or tens of thousands. New perennial crops, like their wild relatives, seem certain to be more resilient to climate change. Without a doubt, they will increase sequestration of carbon. They will reduce the land runoff that is creating coastal dead zones and affecting fisheries, as well as saving and maintaining the quality of scarce surface and ground water. U.S. food security will improve.

Social stability and ecological sustainability resulting from secure food supplies will buy time as we are forced to confront the intersecting issues of climate, population, water and biodiversity."

I don't really understand why perennial crops carry these benefits - does anyone else have familiarity with this particular issue? FYI, here's what Wikipedia has to say:

"Although most of humanity is fed by seeds from annual grain crops, perennial crops provide numerous benefits. Perennial plants often have deep, extensive root systems which can hold soil to prevent erosion, capture dissolved nitrogen before it can contaminate ground and surface water, outcompete weeds (reducing the need for herbicides), and help to mitigate global warming by carbon sequestration. These potential benefits of perennials have resulted in new attempts to increase the seed yield of perennial species, which could result in the creation of new perennial grain crops."