I'm surprised that there is much concern expressed about securing luggage because I've been travelling extensively for very many years and have never ever bothered about locking luggage. For one thing I've always thought that security might need to open it when it's outside my sight and in any case I can't be bothered with messing about with locks. On the other hand I don't put anything of high value in checked luggage. Any valuable items I keep with me as hand luggage.
Quite agree, vanmunchen. I can't speak for others who take vast quantities of luggage with them or why, but for myself, I prefer to go hand-luggage-only and send anything really vital or valuable by a reputable courier. Many years ago, a sage traveller gave me this advice: When packing for a trip, lay everything out on the bed. Then put half of it back and take twice the money. It has proved to be sage advice indeed.