I think some of the buddy walks and mda events are exploiting the kids. What do doctors think?

It is okay. As long the inttention are wright and the walk done with reason. Think of it as family event.Good luck.
Common sense. Motives are never pure. People do make their living helping / trying to help these unfortunate children. For the most part, these folks are driven at least some by altruism. In many places in the world, handicapped children are simply kept isolated, neglected, and ignored. I'd prefer the fun of going out and visiting with others, 'exploitation' or no. Just my thoughts.