Although I can appreciate how some animals will only take live, your type of mentality always amazes me. Once you restrain the animal to a captive environment, it becomes just that - a captive animal, and ceases to be a "savage predator." It is our responsibility as the keeper to provide the animal with a safe environment - this does not include tossing in a potentially live threatening variable. You supervise you say? I would like to see you get in between the bite to the snake's eye that a mouse struggling for its life is more than capable to inflict. It's just not worth it, especially if your animal will take f/t. One quick bite is all it takes for a fatal infection.
It's also not merely a matter of the snake's safety from physical trauma: f/t prey items are lower in parasites after having been frozen and are more easily digested (owing to the tissue damage from growing ice crystals).
The issue at hand is not that snake's make bad pets so I really cannot fathom the relevance of your "don't buy dogs" comment.
But anyway, do what you like, I have no problem with what you do; what you eat won't make me fat, so what do I care?? Just understand that your methods may not be the best for your animals.
I apologize if you don't like the pic but I wasn't expecting anyone to like it, it's a difficult image for us herp-lovers. But it is a perfect representation of the old adage "A picture is worth a thousand words."