As the papa of a gorgeous little Miniature American Eskimo dog, I’m in total agreement with the spirit of Jeff’s post.
We value pets because they provide us with a level of visibility, much like friends and lovers do, but obviously not to the same extent and degree of richness (but sometimes pretty close!)
Mammals such as cats and dogs have a greater range of responses, expressions and actions and are therefore able to provide a greater level of visibility compared to, say, a goldfish. In other words: what Joe M. said.
Causing of needless harm and pain to an animal for its own sake is surely a symptom of serious psychological problems. What are they gaining from the animal’s pain? What are they reacting to? Sickos clutching the “animals don’t have rights” straw to rationalize their own psychosis give me the creeps. (There was actually someone who used to post on SOLO exactly like this – “they have no rights, I can do what I want” – can’t remember their name, though.) Unfortunately, apart from the “property rights” angle, there is no recourse for these psychos apart from richly deserved public exposure and contempt.