I think for every culture or era in which this is supposedly "common" I could find several in which it is not. Whatever floats your boat I guess. I find even wakes or "viewings" to be barbaric and even traumatizing, and I've been subject to countless dozens of them since my grandparents died when I was 3-4. Here's your Grammy little boy, and she's stiff and gray as a plank! OK, here's your scary old Grandpa now! And your little 8 year old cousin that you loved so much!
I want to remember people as they were when they were alive. Last weekend I went to probably the "best" funeral I've ever been to, with a closed casket and a celebration of the person's life. I'm sure if I'd asked to open the box and take a picture his son would have clocked me. As I said to each his own, but you also have to keep in mind how offensive this is to some.