That's a very good question.
To my knowledge, any of the victims I know do appear, and they read the victim impact statement.
I would like to say about the victim impact statement that it is not a statement in which you can go in and spew whatever you feel you want to spew. There are definite questions that are written out for you, which the victim has to answer. It's fairly straightforward.
That's a very good question, though. It should be worth looking at.