This is true, but beans also have some of the highest quality carbs around. Slow digesting and plenty of fiber not to mention a sizable portion of incomplete protein. The problem is CANNED beans sometimes have added sugar or even high fructose corn syrup. Preservatives too.
If the canned beans don't have added sugar or HFCS then this looks like a good recipe if used wisely. You could also soak and cook your own beans.