why is it necessary to rinse so often after getting your wisdom teeth removed?!

The reason is because you have open wounds in your mouth. Just like any other surgery there are cuts to be healed. Also think about it, our mouths are really rather dirty lol. Food, germs, and other foreign bacteria can get into your mouth soo easily. You wouldn't germs to get into your mouth wounds and infect them would you? No that would be terribly unpleasant. So its up to you if you want to follow the doctor's orders, I would. Even if it seems excessive I'd rather be excessive than have a mouth infection.

Are you sure they said that much? Seems excessive maybe it was more like 20-30 seconds 4 times a day. You can call the doctor to ask.