I generally allow Jurors to ask questions in civil cases. See MCIVJI 2.11.
Attorneys will be given the opportunity to see the question before it asked and to place an objection on the record outside the presence of the jury. I have allowed this procedure in over 20 civil jury trials and there are usually no objections to the questions. Often Jurors did not hear or understand an answer and the Witness is only repeating what they said earlier. By resolving this matter up in the Juror's mind it allows the Juror to concentrate other aspects of the case. Sometimes Jurors are asking questions about something that will be covered by the next witness, and when that occurs I will advise the Juror that they should be getting the answer to this soon.
Questions Benefit Jurors & Being Thorough
My experience suggests that jurors are more attentive if they have the opportunity to ask questions. Sometimes the question indicate that a juror is troubled by a certain aspect of the case which allows the attorneys to cover that area more thoroughly with future witnesses.