Salam Mohammad,
If you have only one controller then you can configure everything from the controller and no need for the WCS for configuration.
However, WCS is also used for history reporting. It also shows you info in graphs (like client count on each SSID, number of up and down APs...etc) also keeps AP status history, alarms and events, WIDS messages..etc. in WCS those are kept to be used later while in WLC you can only see the current status of the wireless network.
For example, you can ask the WCS to show you the number of clients during the last 3 months (because it keeps the history) while you can not do that request from WLC (because it keeps no history).
So, if you are OK to live without those history reports then you do not have to buy WCS.
HTH
Amjad
Rating useful replies is more useful than saying "Thank you"
Rating useful replies is more useful than saying "Thank you"