It used to be quite common. I took photos of my wife's grandmother in her casket, at my mother in law's request, but have only viewed them maybe once. My wife and mother in law have never seen them. I also took a few pictures of family members not normally together.
I did not take any pictures during my father in law's funeral, although I brought my camera in case I was asked. My MIL expressed afterwards that she wished I had and forgot to ask. I feel it would have been difficult, and I felt like a number of people were staring at me during my wife's grandmother's service.