The weight of something that is typically mounted to a wall seems very relevant. Most TV mounts are not rated to hold the weight of a plasma TV. A poorly installed or insufficient mount could definitely fail.
Plasma TVs not mounted to the wall are also concerning for safety reasons. A plasma TV tipped onto a young child would likely cause significant injury above and beyond what an LCD would cause.
I loved my plasma but I feel like the weight was a real issue.
Refrigerators, stoves, and washing machines are rarely suspended from walls or situated on consoles from which they could easily be tipped over; televisions, OTOH...