I agree that the majority of the dogs here are sociable and love to play and love people. I also agree that there are many responsible pet owners that wander the island with their dogs and the animals are well behaved.
I have seen many more potentially vicious dogs than you have. And I have seen the dog bites to both full time residents and tourists that were attacked while they were riding bikes up and down the beach.
Indeed many kids (and their grown-ups) are cruel to animals here - it is one of the few behaviors that I find terribly upsetting.