I used to be of that view. Now, I'm not so sure.
Last year, my wife's grandmother passed away. My wife was very close to her, and through her, my daughter had come to be close to her as well. (Sorry for that crappy sentence, but I'm too lazy to clean it up.) My daughter was fine at the time of the funeral. I was somewhat dubious about bringing her to the open casket wake, but decided it was better to let her have that sense of closure (even though I figured she might not fully appreciate it until much later). She stood for several minutes looking at "Grammy", then touched her hand and face. A little later, she asked to return to the casket to look at it one more time.
To the extent I've been able to tell, it was very helpful to her in coming to terms with her great-grandmother's death - which is the first time she's had to confront the issue in a meaningful way. Given that it can be a difficult issue for children -- and often adults, for that matter -- to process, I think that seeing Grammy in her new "state" helped her to understand the change that had taken place.
I would imagine that for some adults as well, the visualization is helpful in achieving a sense of closure, "letting go", etc.