I don't have any hard studies either way, which is why I'm asking here.
However, regardless of health/environment/whatever else, it doesn't make financial sense to me either. It's going to cost over $3,000,000 the first year and about half a million yearly after that, and that cost will of course be passed on in the water bill. The vast majority of the water that is treated is not used for drinking - it's used for baths, showers, irrigation, swimming pools, washing cars, washing dishes, toilets, washing hands, watering and bathing pets and livestock, cleaning, laundry, industrial and manufacturing uses, and so on. Only about 5% of the treated water is used as drinking water, and of that many people would use filters to then remove the fluoride. It would make better financial sense for those who want fluoride to just buy fluoridated toothpastes, mouthwash, fluoride rinses, etc.
I have (obviously) not had fluoride in my drinking water since I was 5 years old and moved to this city (the city I lived in previously did have fluoridated drinking water), and I have never had a cavity, so the cavity prevention point seems kind of dumb. Brush your teeth and you'll be fine (yup, just brushing, I rarely floss because I hate flossing).
I do buy bottled water for me dogs because the pipe leading up to my room (where I feed and water my dogs) is made of lead. I don't use the water from that sink for myself, so I don't use it for my dogs either. That said, the water I use is bottled from city water, and just is filtered. In a pinch I'll even just go downstairs and refill it in the kitchen. Thus far I don't mind our city drinking water, it's just that one lead pipe that I won't use (all the other pipes were replaced when we were switched from well water to city water several years ago, but that one was not).