We love our animals dearly. 2 cats (hers) and 1 dog (mine) in our household.
They certainly do curtail our freedom somewhat, though, make it harder to travel, and they do cost some money. I don't think we'll be running right out to replace them when they die, though I imagine I will want a dog again someday.
One thing I won't do is pay ridiculous amounts of money to keep him alive if he gets sick or badly injured. In the end he's not a person, he's a dog, and I'm not going to spend my whole emergency fund to save a dog, even if he is the best dog evar.
He also provides services. We have lived several places with high property crime (including our current neighborhood), and never once had a breakin or anything stolen or damaged. My old roommates got broken into right after I moved out (twice!), and one of them has had subsequent apartments burglarized several times since. Houses have been broken into on this block several times in the past few months, but so far we're clear--and I expect it's partly because we have a big dog with big teeth, an even bigger bark, and a very ominous growl which he deploys whenever he detects an unidentified person at the door. I think he's an excellent theft deterrent. Not getting burgled is worth the ~$45/mo in food (he eats bone-in raw chicken, giblets, beef meat/liver/heart, and eggs) and occasional vaccine boosters, and then some. Plus he's an excellent exercise buddy and generally a fun little dude.
He was a skinny, nervous, tick-infested little mutt from the pound when we got him, and now he's a big, strong, happy mutt and about the best dog I could have asked for. :-) I would totally recommend getting a pound mutt to anyone thinking about a dog, btw. Cheaper, just as great as any purebred, and usually WAY fewer health issues (he's had NO unexpected veterinary expenses in 5 years of ownership).