Your claims that (1) the food pyramid put whole grains at the base, and (2) that there is any consensus at all that a healthy diet should include more whole grains than fruit and vegetables (which is what "being at the base of the pyramid" means).
As for whole grains vs fruit vs vegetables, here's a SR and MA of studies looking at different food groups and the RR of all cause mortality: https://www.sciencedirect.com/science/article/pii/S000291652...
Three servings of whole grains per day: 0.79 (21% reduction in ACM) Three servings of vegetables per day: 0.89 (11% reduction in ACM) Three servings of fruit per day: 0.90 (10% reduction in ACM)
So the evidence seems to support the suggestion that consumers should focus on whole grain consumption as a base for their diet.