Defense Acquisition exists to acquire a service, tool, or product needed to accomplish a mission or function in better fashion, more efficiently, more effectively, less cost.
In an earlier and simpler time, the requirement was for rifles, bullets, clothes, food that supported soldiers in the field. As time and technology moved forward, the tools to accomplish our defense became more complicated. Better swords, better shields, faster ships, bigger firepower, stealthier information gathering, more data points, more zip, more zap, more bang for the buck.
Clearly defense warfighters/users must focus on their operational tasks, so an acquisition corps is given the responsibility to get what the soldiers, sailors, and airmen need and with that comes a disconnect and separation between those who are responsible to support, train and equip and those who are responsible to execute the defense missions.
No one in the executive chain has the appropriations or authority to buy anything unless it is provided by the Congress. Those on the Hill responsible for both the authorization and appropriations are living a tri-polar existence in terms of providing for the common national defense, listening to the constituents who placed them there, and following their own personal agendas (hopefully in that order).
And then there are the suppliers, supporters, and industries that provide the goods and services. Some are good, some are not, all are in business to make money (Don’t ever misplace that fact — if they don’t make a fair profit, they go away. Not good for anyone.)
At a high level, there should be no intent to buy something that is not needed or to spend money, time, or resources on things that don’t improve the mission or the business function. The problem is that there is never really full agreement on what is needed.
The FAR, DOD 5000.0 and all other rules and regulations are in place to ensure funds provided are spent wisely to acquire commodities and services that meet a need. The first version of whatever the original acquisition rules were about were pretty simple – buy this for that general, keep track of what you did, report back to the Congress on how you spent the money. Somebody along the way didn’t like the result, so a change was implemented that provided more oversight to ensure the purchase met the original description. Some competing supplier thought they should have a piece of the pie and convinced their Congressman to legislate more fairness. Greater fairness meant more oversight. More oversight meant more need to prepare for the oversight. More preparation time meant less time to focus on delivery and performance and more time to answer questions about delivery and performance.
Our democracy is based upon everyone having a voice. Unfortunately, in a world of ever evolving technology, communication, and information sharing, there are so many voices that it is difficult to focus on the basic need in a way that cannot be disputed by someone else in the food fight. The process becomes more complicated with more irons in the fire and dogs in the fight. Everyone wants to be heard – few want to listen. 

We can acquire needs quickly and efficiently when absolutely necessary. There are black programs in every service and agency that are in place to make it so. When all is considered there are but a handful of rules that absolutely must be followed in order to ensure products and services are delivered quickly, efficiently, and effectively. They are carried out by the best of the best, who know the touch points, the requirements, the authorization and appropriations processes, and where the lines exist that cannot be crossed. All the rest is oversight that keeps information flowing, but mostly eats up a lot of time and money. These are the best practices that our acquisition process must figure out how to emulate without affecting safety, performance, or breaking the law.