If you had a relative (gt grandad, for example) who died in the 1940's (for example) and you had never seen a photo of them in all your time researching family history, would you (given the chance) view their exhumed corpse?
No, I wouldn't want to.
Exhumations require special permission in the UK (Coroner - Home Office - Police I think too).
Usually a detailed Archaeological Method study too (for Planning proposals), where buildings, driveways, railways, airports, or roads etc., cross cemeteries, with on-site recording during the works to make a complete permanent M.I. record and coffin plate etc record
Many Sextons Plans are now missing, not all graves had Memorials originally and many have no Memorials today.
Some graves have been exhumed of those who died in the Titanic disaster, who were found and buried shortly afterward, to try and identify remains. One grave only had the brass coffin plate in.
----------
I saw some exhumations on film and only several (out of hundreds being exhumed there) of persons who had been embalmed, wrapped and were still in dry complete Coffins in bone dry ground and were in a good state of at death preservation.
----------
In Parish Church Cemeteries they were stacked, often disturbing the grave, body and remains underneath.
-----------
I think tracing the whole family (can be a large / impossible job for some), as more distant relatives (if a collector / hoarder) might / might not still have photographs (like Cousins of Parents and Grandparents) who identified photographs before their families died off.
My Grandparent's Wedding photo was in the newspaper 90 years ago. Although, we did track down an original and several other photos (from my Grandmother's remarriage family, descendants).
Mark