Modern day domestic dog's or Canis lupus familiaris" or "Canis familiaris" are the best thing to ever happen to man kind.
I can't argue with that based on how many different varieties there are and how many benefits they provide. Plus they are fun to be around.
Dogs were the first species to be domesticated and now I don't think they can do with out us. 
I didn't know they were the first, maybe that was to help with hunting? Anyway that's sad that we've made them dependent on us, hopefully we can improve that situation somehow.
It may be to late. Now that we have domesticated them they  thrive on a starch-rich diet that would be inadequate for other canid species.
I see, I feel like we have a responsibility to look after them since we caused this diet change. Also especially since we've been using their skills to augment and assist ours.
Sadly that diet dose not exist in nature. They do perform many important things for us such as hunting, herding, pulling loads, protection, assisting police and military, companionship and, more recently, aiding handicapped individuals and therapeutic roles. So we have to take care of them.
Yea when I look at your description of what they do, they basically have jobs and do quite well at them. At least if we have to be together we are working together well in numerous ways so I think it's beneficial.