Comparing this with surgery is not fair, I think. Here (with a food like soylent) the gains are low and the risks are high. With surgery, the risks are high but so are the gains. Before you go into surgery you're given a list of 10 ways you might die if something goes wrong. Oftentimes, though, the alternative is certain death (in the very near future).

Edit: I was replying to "But we have made surgery mistakes along the way". On a second reading, I notice that you did not actually mean to imply "it was necessary there so it's necessary here".