In poor traction situations a wider tire acts like a ski. Snow, standing water and mud, for example. In these situations (except for packed snow) you want to get through the problem down to where traction exists, so narrower is better.
Like Scotty says, each situation and combination of circumstances prescribes a certain 'Ideal' tire. The problem is, we don't usually have a rack full of different tires like a race team, and no one to swap them out every time the conditions warrant. So we select the tire that will do us the most good in the majority of situations we encounter. This always requires compromise.
Then, hopefully, we are aware of the weaknesses of our chosen tire and ride accordingly when the tire is not optimal for that particular condition.