It is impossible to move any higher in terms of complexity of thought without comprehension, and the vast majority of adult tasks require the ability to do more than simply remember items and concepts. Bloom's taxonomy contains a hierarchy of complexity regarding thought, and comprehension is only the second category from the bottom. A failure to achieve this level makes thriving as an adult virtually impossible.
The levels above comprehension in Bloom's taxomony are, in ascending order, application, analysis, synthesis and evaluation. Application involves the ability to take one concept and put it to work in a different situation. For example, understanding how pliers work allows one to apply the same technique that accompanies removing an old nail from a board to removing a splinter from one's hand. While the tool differs, splinters generally require tweezers instead of pliers, the motion and the process are quite similar.
Analysis, synthesis and evaluation involve the ability to take information and break it into its component parts, put them back together to make something new and then provide a judgment on the entire quality of the process. Without these critical thinking skills, people lack the ability to make decisions that impact their lives significantly.