Following instructions is important because, in many instances, if the instructions are not followed, then the desired result or goal cannot be achieved. There are numerous instances that can be given to exemplify this, like the presence of laws, the rules to an academic exam or the steps written out in a cooking recipe.
Instructions are an important aspect to the academic setting. Many students, who may be extremely smart and able minded, can still receive poor grades if they fail to understand and follow the instructions of their exams and other academic assessments. If one is having trouble following directions, they should try to examine why this is happening. The reason could be an underlying problem, like a disinterest in the subject matter, or it may very well be that the professor or teacher gives instructions that are confusing and hard to understand.
Nevertheless, following instructions is an important skill to have in life, simply because it shows up in so many contexts, like playing sports, cooking food or performing any other kind of logical task that requires a sequential set of steps to be done in order.
The numerous laws and regulations set up around the world are like a legislative form of instructions, designed to maintain order and keep people from doing morally wrong things or cheating a logical system that everyone else dutifully follows. Many of these instructions, which we call laws and constitutions, exist so the world has competent governments, effective legal systems and doesn't fall into general chaos.