Edvard stated:
Also, the entire thing with safe words, for example. What is the thrill if you can stop, or know that the other person can stop it anytime? I've had only a couple of one night stands where the woman was dominant and I suspected crazy enough to make it believable for me, and the thrill was amazing. Without that edge, the thrill is not that intense for me.
Obviously it's a total boner killer to have to stop for any reason, but it's what ensures respect and trust for being able to have a future go at the same sort of thing. What you're mentioning applies closer to a one night stand model, a dynamic that changes once you're more focused on something closer to permanency, as permanency requires trust. I'm also sure, unless you have a deathwish, that if someone was crazy enough, losing themselves to the passion to a potentially murderous degree, to the degree of breaking bones perhaps, that you'd wish you had that safe word. No one's invincible.
For me, it's fun when they could stop, but don't. From the deliverer's standpoint, it makes it easier to grant the other person respect for how much they could take, it makes it into an admission of weakness from the receiver that can be fun to resist the urge of, and it becomes a challenge of the wills for both people involved. The sadist could be trying to make the person give up, have that as a notch under their belt, just how the masochist could refuse to give in, knowing that the option to is always there, always within reach, but that s/he'd be a complete killjoy pussy if it's said before it needs to be.
For myself, it'd be a mark of shame to have to use it, but I'd still rather have it and refuse to use it.
Cricket stated: source post
I agree that there should be a balance of sorts, though I'm not certain that it needs to be driven by fear. A healthy dose of consequence-awareness and the desire to prevent said consequences could serve just as well.
It's not the same. Fear gives room for drive, obsession, awareness, sensitivity, and relation to another's fears, and with that a reason to practice it far more often than one without it. A person without fear has plenty of their own advantages, but also will lack the level of analysis that will follow an overly cautious person from the reduced perception of it's necessity. Someone from an abusive home for instance will be that much more trained to be wary of threats than someone who never feels threatened (a point they tried to make about a character in the show Lie to Me).
Daario Naharis talks about this lightly in Game of Thrones: