It looks better, and seems more appropriate, to have cuffs on a pair of pants made of heavier fabric (flannel, tweed, herringbone, heavy wool, etc.) and worn in the winter. Not only does it add the likeness of wearing an extra 'layer' which is best suited for colder months, but it also adds weight to the bottom of your wool trousers causing them to drape better as they fall. To add a more stylish element, make your cuffs a little wider than your average Joe. Go with 1 3/4" or 2", a look that is popular among fashionistos rights now.
On the other hand, the warmer and more nonchalant months of summer call for a regular hem, a little shorter to show a hint of ankle. Summer clothing, besides being more casual in general, can be simpler and have less details. Therefore, light-weight wools, linens and definitely cottons should not be cuffed.
Hope this helps.
Yours in style, Style Blogger.