Lara said she's interested in other opinions, and the following is my personal opinion. To me, there are values more important than efficiency.
Quality of life comes to mind.
Yes, but I do not want to live on gruel and bread. My personal preference would be to grow more beef on grass. My personal preference would be to reduce world population. I hope not. I agree that animal waste is not being put to good use, but I find it very hard to believe that there is more than could be put to use.