Check the link I posted above, Zino, from Erowid, which I'll place below, too. Simply scroll down to the heading that says "Withdrawal symptoms." You're filtering what you're saying through your own experience, and just because you haven't experienced withdrawal symptoms doesn't mean other people do not. Every body and brain are different, and some people do have those symptoms. A better term for them would be "cessation side effects" because, again, they're not classic craving-sick withdrawal like what occurs with narcotics. But in plenty of people, those symptoms do happen. I urge everyone to open up your minds and look past your own personal experiences on this. That's a skill that'll come in handy in your future lives in all sorts of areas.
Erowid Cannabis (Marijuana) Vault : Effects