Going cold turkey is an ego-motivated action, in my opinion. It's the 'If I can endure this acute suffering and beat it, then I'm stronger for it' attitude, and gives a false sense of inflated accomplishment. The reality is that you put yourself through needless torment so you could feel better about yourself, while a rational person whose goal is to actually beat the addiction realizes that their chance of returning to the substance increases substantially with how bad the withdrawal symptoms are.
If you want to quit, do everything you can so that you don't go back to ingesting the substance in question. That means reducing the chances you'll relapse because withdrawal fucking sucks and the only thing that will fix it is either waiting or using again. Guess which one your brain will try to convince you to do (hint: its the one with the least amount of immediate suffering)?