DRAC is used for out-of-band control. You would use it when regular access to machine is not possible, for example because it crashed, or you cut off access to it via local firewall on machine etc.
Then (instead of getting in your car and driving to location) you could DRAC to get console access to machine to try to fix it there, or to power-cycle it remotely etc.
You can also use it for STONITH if you are building HA cluster or similar.