There could be a million and one reasons for a dog to be on a lead, you can't jump to the assumption that the dog has a compromised life because it is out on one. for example, i am taking Alfie for the briefest of lead walks at the moment, please don't feel sorry he is on lead, please feel sorry that he had a very bad fracture of his elbow a month ago. Worry about your own dog and not other people's and as others have said it is rather bad form to let a dog not under control run up to other dogs on lead who are looked after with the best of intent.