If you are writing to guys simply because they write back, expect them to stop answering questions. Just like how it is known that guys who sign are getting hit more often for TTM, after awhile they will slow down, stop or charge. Same will happen with those who "write" back as the OCD collectors will abuse this. It should be NATURAL that they write back, not that you force questions on them so that you have a signed questionnaire from them. It is time consuming for them to write back and I just have a feeling that collectors online will abuse this.
I agree with you. I don't "force" questions or send a questionnaire for them. I ask two to three simple questions and thank them for their time.
I've interviewed a lot of retired players for both my upcoming book and articles that I have written. Many of them said they're tired of getting the generic questions of, "Who was the toughest hitter / pitcher? Favorite place to play? Debut, first hit, etc." They feel most of that information can be looked up and that all of the pitchers / hitters were tough or they wouldn't have been in the majors.