Yeah, taking Roy out of the equation this is a horrible break. One thing Roy mentions about visiting kids is that it sounds like a great idea but it's pretty emotionally straining on the person visiting too. Any medical professional can tell you about the stress of dealing with that kind of stuff regularly.
So for all the "athletes should do this", I imagine doing it on a weekly or even monthly basis can get very depressing. Most of us reading about it do not experience that, nor would we want to make weekly trips over to the ER to sit with families in tears.
We see the smiles of the kids when a celebrity visits, but the person visiting is staring down the injustice, the loss of innocence, and the pain of not just the child but the family. It may be "the least they can do", but it's more than most people put themselves through. Going through it with family and friends is tough enough, let alone strangers.