I know quite a number of women who are into this fantasy.
I compare it to its male analogy: castration, that turns on many men as well.
Part of the thrill sure is that it's about the body parts that we generally protect most, isn't it? So it's the biggest possible taboo that is broken...
My first girlfriend, with whom I discovered BDSM was greatly turned on by this fantasy, while being well aware that fantasy and reality are two different pairs of shoes. I'll get back to that point later.
So I made this part of our play, eventually bringing a knife to her breasts and whispering into her ear "now the moment has come..." or something along those lines.
It didn't take much to bring her to a violent orgasm, with her mind cinema rolling at warp speed
What was exciting for me...
Does the fantasy turn me on as a Dom: Yes it does, for the same reason as it turns on the girl.
Would I ever want to do more than "playing a bit" and make her mind cinema go: No! Not as long as women can't grow new breasts like sharks new teeth
I adore breasts, they provoke a "tender impulse" in me and hurting them is almost like hurting myself. (Again: Breaking a taboo...)
What doesn't prevent me to hurt them... IF a girl likes that (what many do).
One has to be well aware of the nice fantasy and the nasty reality of the act. Our fantasy is "what we'd like it to be (she excited despite her will etc, breasts keeping their shape when cut and nice firm meat) while the reality would reveal that it's a bloody mess and breast are just fat and not chicken breast meat
So, as a fantasy it's fine, much more widespread as one would think.