Is it Fair to Leave a Dog Alone All Day?

I think the greatest solution to this common problem and a big help to the overpopulation of dogs in shelters is to get your pack animal a dog to keep him company when he is alone.
   
Of course you would have to be able to afford it and they would have to get along well with each other.

My guy is 5 years old and it has just been the two of us since he was 6 weeks old. When I first got him, I worked down the road and was able to come home and check on him at lunch hour. Now, I work a little further away and cannot get home at lunch as often as I'd like. We go for a walk in the morning, a walk when I get home, and a walk before calling it a night. He has free reign of my home, lots of toys and rawhide and nylabones to keep him content. His only requirement is a window to look out at the world during his day. He's a perfect gentleman. When I travel, he goes with me. He loves to hang his head out the window. I did kennel him for the first 2 years during the day, but slowly started introducing him to the whole house.

I'm fortunate enough to live on a fenced acre in the woods, so my dogs have free rein of the house and yard via a dog door. I usually aim for at least an hour of play time twice a day for my Lab mix, and a short swim for my elderly GR. If I'm gone all day, I'll usually have someone come over and throw the ball for my Lab and take him for a walk. If I'm late, all my animals are fed and checked on by a neighbor.
   
A good example of leaving animals alone for hours on end are my neighbor's Beagle and Lab mix (my dog's brother). Both these dogs live on 20 unfenced acres and usually end up spending the day, and sometimes the entire night, at my house. They're lonely and bored so they leave their property and go where they know there will be pets and cookies, not to mention a soft sofa.
   
Personally, I don't think it's fair to leave animals alone for hours on end, especially if they're crated. However, I can appreciate the fact that it's essential due to work schedules. As long as the dog gets plenty of together time with the owner, and lots of play/walk time, I don't think the dog will suffer unduly if left along. However, if the owner is gone for more than eight hours, I believe it's wise to have someone take the dog out to relieve itself and have fifteen minutes or so of play time. Doing this twice during the day would be ideal, especially with a young, active dog.