Why does Nurse Ratched value order in the ward in One Flew Over the Cuckoo's Nest?

Nurse Ratched's primary motivation throughout the
narrative is one of control.  She seeks to control the patients in the ward with a sense
of totality that is beyond question and above reproach.  The doctors are only peripheral
because the ward is hers, and she ensures that her embrace of rules and order is done to
consolidate her own power of the patients.  She views control as the most important
element in the life of her patients.  This is shown not to be maternalistic, as much as
representative of a totality where structure and order is the most important element. 
Her background as an Army nurse is present as there is a clear chain of command and she
starts it.  Nurse Ratched represents that element of society and political order that
values control over all, including personal expression and individual entitlements. 
McMurphy's presence represents the anomaly that always is present to such orders,
demanding social and political change.  In the end, her power driven sense of control is
shown, and while McMurphy might have failed for freedom in his own setting, his example
towards her has inspired others to bring down her environment of control and
dominance.