Some of you who are against carrying children through the finish line and having family support around- what is your opinion of Dick Hoyt?
http://www.teamhoyt.com He carries his son through the entire course!
Many of these events are family events. Many of us have spouses and children who put up with our long hours of training. Being able to have them at the race is a great boost. While I don't allow my 5 year old to run through the chute with me- he is right on the side lines yelling- "Go faster Mommy! Go Faster!" So I have to put on a good hard finish for him. My husband will then bring him around to the back of the chute where I'll let him wear my medal and ask him if I ran fast enough for him.
As for having a group of people in front of you slowing you down so they can get a family photo finish- trying to get through a line of slower swimmers, its the same as having the people walk through transition in front of you or the bikers who ride all the way to the left so you can't pass them, cars pulling out in front of you on the course, lack of directions on the course- its just another item to deal with. It depends on how you want to deal with it. Jump in the photo with them and wave your hands all over the place. Yell "coming through" and plow through them. Slow down and wait so you can have your own finish photo.
If this is something race officials don't want to happen, then they can make an announcement prior to the race, make announcements throughout the race at the finish line warning against this and offering family photos in another area after the race. The Disney Marathon offered a post race picture area so you could have one taken with family and friends.