Another omniscient poster. What are the causes of smoke? Among them could be a wheel well fire. And what might that impair? Perhaps the brakes? If Swissair 111 had headed direct for Halifax upon the smoke in the cabin, how do you think they might have landed? Given how quickly the fire progressed, it was not going to be pretty.
PAX are not briefed for a multitude of abnormal landing situations (assuming the crew could even know exactly what abnormal landing situation they were in). They are briefed for one, which is a call of BRACE. And how did that call harm things?