Trouser bottoms have long varied in width, from the 17" Oxford bags of the thirties to the six inches of the Conduit Cut in the sixties. Today, they range from half a foot to perhaps twice that.
Fashion aside, the width of a man's trouser bottoms should be individually determined by the size of his thighs, so the fall of the trouser is properly scaled. This is of course another reason why tailored clothing should ideally be made for each individual.
There are a number of modern designers whose offerings have deliberately narrow trousers, perhaps most prominently Mr. Tom Ford. Nothing wrong with that, but it helps explain why the ready to wear version of those clothes looks proportionate only on the thin.