For the 6-year programs it is (obviously) a bit of overkill, since they accept people directly out of high school.
For the 4/5-year graduate programs, it can't hurt... but the only way to get each school's take on that is to contact the schools themselves. Their individual criteria (and value on a graduate degree) could vary considerably. It's certainly worth emailing/calling all of the schools on your list.
"When I haven't any blue... I use red."
- Pablo Picasso
"You cannot allow any of your people to avoid the brutal facts. If they start living in a dream world, it's going to be bad."
- Marine General James "Mad Dog" Mattis