I'm a Labrador Retriever owner. As a Newfoundlander, that isn't too unusual, since they were developed here on the Island, along with the Newfoundland Dog. Both were meant to be big dogs with lots of stamina that handled the cold well.
You have to realize that our salt water: The North Atlantic, is rarely over 1 degree Celcius in Summer. You have less than 12 minutes before hypothermia sets in if you go in the water unprotected by a Mustang survival suit, wet, dry suit. Unless you have lots of "natural" protection, you aren't coming out alive after an hour or two. We use our Labs to retrieve sea ducks, turrs (murres), snipe and bull birds that are shot from shore and when a floating jigger can't reach them.
At the same time, we use them in fresh water as well, and they do retrieve their fair share of blacks, mallards, teal, wood, goldeneye ducks, as well as Canada Geese. However, the water is again extremely cold. At the height of summer, fresh water ponds, lakes rarely have water temps above 15 degrees C. You can imagine what the water is like in October/November. We have had snow as late as June and as early as September, so you need a big dog with lots of strength and stamina to handle the elements.
That strength and stamina also comes in handy during late season partridge/ruffed grouse/spruce grouse hunts over snow covered bogs and barrens. Snow shouldn't bother him.
My six month old pup Bruiser(male, chocolate), is about 75 lbs right now and still growing. I have swithched him to Medi-Cal Adolescent, it is a specially formulated dry dog food available from my vet. It evens out growth spurts for large breed dogs and allows them to grow at a steadier pace without undue stress being put on joints and bones. They grow just as big, but at a pace that is easier on their system overall. Bruiser is in top physical shape and is not an obese dog by any stretch of the imagination. He has absolutely no problems handling water work, despite the cold.
I think smaller Labs and the AKC conformation standards, etc... is a by-product of the English influence and show-dog cirucit that has been the ruin of many a great breed. Labs are meant to be working dogs who are happiest playing in one of the harshest climates in North America, not dog show dandies. I asked my Grandfather about it, and he told me that our Labs had always been big dogs, as far back as he could remember and was the same in his grandfather's day.
Bruiser will break 100 lbs, if not more, and I don't see that as "undesireable" despite what the AKC "Standard" says. Look what such arbitrary descriptions and subsequent breeding has done to breeds like the Irish Setter? God help us if our Labs end up the same way...