Wow, this thread did take an interesting turn.
Back to dog boots for a moment, someone mentioned that "some dog's feet are softer than others" from being indoors. This is a partial truth, however, it is important to note that rocks, especially scree rocks, can be quite sharp and could cut the pads or the delicate skin between the toes. Also, the surface of the pad can wear down over rough terrain as well, no matter how well conditioned they are to being outside. So whether or not you choose to have your dog wear booties, keep a close eye on their feet and have a plan for if your four-legged friend gets a cut or has sore feet. This also applies to dogs that do wear boots, because they can get rubs on their legs and tops of their toes. Just like a person with blisters, a dog with sore feet is not a happy one and you always want it to be a good experience for your dog as well as you. The same for dog packs, which can be used well or, in the case of an overweight Lab I saw hiking a (to remain anonymous) 14er, a hindrance and a health concern. As a general rule, if I'm going on a hike I bring a first-aid kit for me, and one for my dog that includes: hydration salts (mostly for the flavoring that it adds to the water, which encourages my dog to drink), vetwrap, cotton stretch bandaging, zinc oxide sunscreen (for her pink nose) 1/2 inch tape, antibiotic ointment, an instant ice pack, thermometer, bandage scissors, and LOTS of water. Fortunately, most of this is a double of what is in my human pack, so it doesn't take up much space.
To touch on Linda's comment, it saddens me that someone would have such a negative experience with dogs on hiking trails as to want them banned completely. With any hike, but especially with dogs and children, it takes careful planning to insure that you have a good time in the backcountry. Personally, I have had nothing but positive comments while hiking with Taiga, who has been trained to only approach people or other dogs on command and to hike right behind me. If I am not sure that she will follow voice command, she remains leashed. I am always very careful to a: pack out any waste if possible, b: bury it or c: have her go at home before we leave so it isn't an issue. As a biologist, I would never want my animal to have a negative impact on the environment, both flora and fauna. That said, humans leave damage in their wake whenever another path is made up a mountain. Personally, I think it's an issue of balance. Be a responsible owner (which means sometimes leaving furry creatures at home), use leave-no-trace ethics, and respect other hikers and their wishes for a good experience. Thankfully our dogs are legally allowed on many trails, but keeping that privilege rests squarely in the hands of any dog owner that brings their animal into the backcountry.
Such things for example as the grasp of a child's hand in your own, the flavor of an apple, the embrace of a friend or lover...sunlight on rock and leaves, the feel of music, the bark of a tree, the abrasion of granite and sand, the plunge of clear water into a pool, the face of the wind--- what else is there? What else do we need?