Employees and employers interpret their actions differently.  As a manager, I hire employees to accomplish certain jobs.  If they serve their purpose and are no longer necessary in the position they hold, then they can be let go at that point.  From the employees viewpoint, they are being used and then tossed aside.  My argument as a manager is that the employee was hired for a purpose and paid to do the job.  I don't feel that there is anything wrong with this circumstance.  As an employee, if this happened to me, then I move on to a new job.  I probably  would not view this job or employer in a positive light, but why is that?  I was paid to do the job that I was asked to do.  I don't view this as using an employee since they received payment for this.  Also, suppose that the employee was given a specific lay off date 2 months from now.  Is that inappropriate or a nice gesture to give them plenty of notice and time to possibly line up another job?  I understand that in this economy, no one wants to find out that their job is being eliminated, but I don't really understand why that employee might feel used or treated unfairly.
Along that same line of thinking, should a more senior employee have the right to bump another employee out of their job?  I will visit this more in the future as I put some more thought into it.