All work needs to be managed. If there is no formal Manager for a team, or for a project, then people will naturally take on managerial roles.

So if we understand the logic of having a manager, why do they still get a "bad rap".

The most efficient and effective way to get work done is to have an clear organizational structure that has a formal PM role (the Manager). The PM will be accountable to manage the project and the team and carry out work to accomplish a plan.

1 - key thing that will constantly need management is change. Since a project is unique, many things will occur that were not planned for. Change leads to opportunities and threats, so we need to manage both (enhance one and eliminate the other).

2 - second key thing that needs to be managed is that change will bring conflicts between people.  The primary tool to help manage that is to ensure an environment of trust and respect is installed and fostered as the team goes through the stages of development (forming, storming, norming, performing). Understand that change is not only rationale, it also can be emotional.  This is again why management must be formalized to be able to deal with change.

Value and What to Manage
The PM must ensure to manage these aspects and then the value is achieved.  Look at the project lifecycle and the stages it will pass through, and then the key points that need to be managed at each stage.

An example analogy I recently heard from an expert in Leadership (Shoham Adizes), a project is like making an Apple Pie, you need:
1 - apples (or people) - but have to be careful, one bad apple can spoil the entire pie, so manage the team and ensure all are on side, if not, then changes to the team or the level of interaction will need to be adjusted
2 - recipe (plan) - need to know what are we doing and how we are going to do it, manage the plan
3 - cook the pie (systems) - need to manage the work in accordance to the systems, the type of systems will greatly impact the confidence you will have in the quality and amount of monitoring required
4 - presentation (customized to client) - manage the final hand off of the end product or service, what will you do with the pie, will you package it in cardboard or on a plate with flowers and add extra ice cream, sauce and chocolate, served on paper plate or royal china

Management is becoming more and more complex.  In the old days, tangible things were always the most important.  New companies that achieve rapid success are paying much more attention to "intangible assets" such as the structure, systems, acceptance/embracing of the systems and ability of the people to manage work within that environment.  More research is now becoming available to support the value of management and structure and innovative ways to try and measure "intangible aspects of success".

A leading researcher is Ulf Lindberg (with Requisite Organization International Institute) who has published several amazing articles, for example: