I agree whole-heartedly. I get emails from people who visit my website. Most of them write to say they are researching their father's war record after he has gone. Some can't tell you what his unit was or even where in Europe he served. They have a name and maybe some story about visiting Rome.
I try very hard to help anyone learn as much about their father's war time service. If they can provide info as to what infantry company, that can help them learn something about their Dad's unit. If they can provide a date he was wounded, then I can give details as to where his unit was on that date.
But it is much easier to learn details while they are still with us. Even if it seems to be a very insignificant detail. Also, you will be surprised; it seems that if you do your homework first, then they seem more likely to answer your questions. I know my Dad would not talk much about his experiences to just anyone. But if he knew the person had been there or understood what went on, then he would freely talk.
Steve