I remember as a kid, and this probably explains why im a Disney Freak, that I would get so overly excited when I would see a character as I still do today! haha It's just the joy of knowing that Mickey your favorite, or whoever it may be, is actually giving you their autograph.
Just imagine meeting your fav music star and getting their signature.
Another story that my cousin loves to bring up is when I was 16, we were on the monorail and I kid you not, I screamed, "OMG!!! There goes Goofy!!" as we passed through the contemporary resort. All the smaller kids just looked at me as I startled everyone on the monorail!! haha Love it!
Now that I've told my stories.. haha I just think it is worth the time for the kids b/c if they are anything like me, the joy is so overwhelming to just get that autograph and take that picture.