The suggestion from the United Nations that the bugs can be a better choice for food source than the pigs and cattle is because of the sustainability of the bugs as a food source.
The bugs consume much less food, and their food choices have a very wide range, often being very opportunistic eaters. Also, they multiply extremely quick, grow very quickly, and are an excellent source of protein. All of that compared to the pigs and the cattle and their demands, time for growing, and space they occupy, gives the bugs a big advantage.
On the other hand, most of the nations are not willing to try such a move. The reasons for that is that most of the people, especially the ones in the developed and developing world find the bugs disgusting, so consuming them is something that they will never do.