The parties are generally entitled to present their case as they see fit, as long as they stay within the rules of evidence. If they want a straight yes or no, the court will often require the witness to provide one, which keeps lawyers happy, makes the answers clear for the jury, and limits the parties' grounds for appeal.
If a yes or no answer is not as accurate as a more qualified answer, the other lawyer would typically have an opportunity to invite the witness to provide a fuller answer on redirect.
If a yes or no answer is inappropriate because of assumption embedded in the question -- as in your "beating his wife and kids" example -- the question should quickly elicit an objection from the defense attorney, who would note that the question lacks foundation or assumes facts not in evidence. Assuming there isn't any evidence of domestic violence, the court should sustain the objection, in which case the witness would not need to answer at all.