A: To start, you can say that between 2006 and 2010 there were 209 incidents known to the government involving bassinets and cradles and that among those were the deaths of 61 babies.
Back when they made that cradle the idea of what was safe for a baby was vastly different than it is today. Newborns are incredible vulnerable and a lot of new moms don't realize that a lot of the images they have in their head about how babies are handled are not OK anymore. For example, it was once commonplace to have heavy quilts in a baby's sleep environment. And it's clear now that is simply not safe.
The biggest risk to a sleeping baby is suffocation. And that was just not part of the thought process when baby furniture was made a century ago. It's one thing to put the baby into this piece of history for a brief nap while being watched or to have a photo taken. It's entirely another thing to use that as the primary sleeping environment.
Point your family to the stories about babies who lost their lives featured on the Kids in Danger website. Hopefully, they'll see that there are real consequences for ignoring safety in favor of aesthetics.