Hi Naresh - Good perspective on change management.
One of the main reasons for Change Management being considered as an 'Unholy Nexus' is the fact that EVERYONE is not involved in the decision making which seems obvious. The downside is that everyone wants to be a part of the decision making process as it is considered as a matter of pride. Whoever is left out of the process feels he has been wronged and develops a revengeful state of mind. The second reason is - Few Take Decision but Many Get Impacted. E.g. Government decides to increase the tax (i know I'm taking a very sensitive subject :)). Very few people take this decision as compared to the larger audience that gets impacted by it. Most of the times, the audience does not know why taxes were increased. What they realize is ONLY the additional burden on them i.e. they don't see the big picture (I'm assuming there is one). This is the third reason
Resistance to change is inherent in humans. For each task (even the smallest or the most mundane of tasks) our brain wires itself in a particular way. Any change, forces it to re-wire itself which is not always an easy task. And hence the stout resistance. Re-wiring would mean you need to put in extra effort to practice the change. We all want to avoid it.
A good change manager pre-empts such challenges early and takes necessary steps to avoid them.