Public Policy Analysis.
You might speculate about the future, based on your study of and knowledge of the past. Not possible to study the future. But based on knowledge of the past it is possible to make some educated guesses about the future, and thus have a plan for if they come to pass. Those plans would have several options for the several possible future events that might happen based on what has happend in the past and on what current conditions are that might provoke or catalyze certain events with some probability that is large enough to make planning for them worthwhile. A plan enables training programs to be developed for skills that are likely to be needed. enables resources to be acquired and positioned where they are likely to be needed. Based on the educated guesses, will more or less manpower, automobiles, tactical weapons, other resources be needed? If it is guessed that less of A will be needed, can part of the budget for A be reallocated to procure more of B, where it is thought that more of B will be needed? With a good solid plan to show to the legislature, it is more likely that projected budget changes can be approved, than with no plan. With a good solid plan in place, it is more likely that the law enforcement needs planned for will be met and accommodated successfully, than with no plan. There will always be events and occurrances that were not foreseen and not planned for. But the habit of planning will make it more likely that even the unforseen will be met successfully.
I think that part of the question refers to projecting trends in the future and why it is important to do so. In my mind, given the ever present threat to national security and the elusive nature of this conflict, law enforcement administrators have to project where the trend of the criminal mind is heading. There have been advances in the field of crime that have to be predicted and understood in order to fully understand how to grapple with it should it become a part of the present. For example, few, if any, understood the potential danger of razors and boxcutters prior to the September 11 attacks. Law enforcement administrators might have to use some type of power of projection in order to fully understand advances in the criminal mindset and approach to criminal activity.
It is clearly important for law enforcement administrators to study the future (as much as we can study something that has not happened yet) so that they weill not be taken by surprise by things that happen.
As things change, so will the challenges that law enforcement will face. For example, as America gets to be less white, law enforcement in some areas of the US will need (at least for a while) officers who can speak Spanish and who, hopefully, have some knowledge of whatever Hispanic group is present in a given area. If administrators can foresee this need (or other coming needs) they can work on getting that particular kind of officers on their forces.