In addition to being one of the most popular religion professors, Alex is one of the busiest and most productive historians on BYU campus. Having had the pleasure of hearing several of his presentations, I can understand his popularity as a teacher. He presents material in a dynamic, entertaining manner, while never compromising complete honesty regarding the past.
Alex loves history, and he loves Joseph Smith. His love for the gospel radiates and is apparent to all those who come in contact with him. It is rare to catch him without an infectious smile.
A better question is why did Alex agree to participate in this project when his plate was so full. The answer is that he is also a great friend.