This strikes me as a common failing of rationality. Personally I've never really noticed it in politics though. People arguing politics from all corners of the spectrum usually know exactly what they want to happen instead, and will advocate for it in great detail. However, in science it is extremely common for known broken theories to be espoused and taught because there's nothing (yet) better. There are many examples from the late 19th/early 20th centuries before quantum mechanics was figured out. For example, the prevailing theory of how the sun worked used a model of gravitational contraction that simply could not have powered the sun for anything like the known age of the earth. That model wasn't really discarded until the 1920s and 30s when Gamow and Teller figured out the nuclear reactions that really did power the sun. There are many examples today, in many fields, where the existing model simply cannot be accurate. Yet until a better model comes along scientists are loath to discard it. This irrationality, this unwillingness to listen to someone who says "This idea is wrong" unless they can also say "and this alternative idea is right" is a major theme of Thomas Kuhn's The Structure of Scientific Revolutions.

Given that no revolution ever produced the system that the people who threw the revolution planned to introduce I don't think that it's an easy case to argue that you need to have a specific plan. Waterfall is no good design paradigma.