Unfortunately, it is the default behavior.  You can always make a second
calendar and use that one for private appointments.  If you obtain Extended
Reminders from http://www.slovaktech.com/extendedreminders.html you can also
fire reminders from this private calendar.

Uh, the idea of having a calendar is to show when you have something/anything
planned.
The idea of having private appts. is to let others know you are not
available at a certain time and it hides the details.

For example, if I have an appt for a herpes test, I don't want everyone to
see the details but I would like people to know I will not be around at that
time. I make it private.

What good would it do for anyone to see your calendar if you do not want
them to know when you are available?

Don't put the private appts on your main calendar.
Create another calendar for you private appts.

Click on "Folder List" on the left side of Outlook.
Right click on the Calendar and select "New Folder".
A box will pop up. Give it a name (Private appts?)
Select Folder contains "Calendar Items".
Then select somewhere to put it.

Put your private appts in this calendar.