Do you think that it's feasible for an NPC in a porn game not to 'wear' their Dom/Sub 'hat' all the time and to leave most of their attitude at the bedroom door, while still being a pronounced bona fide Dom/Sub and being of any interest to people who like the kink?
To quote a rather hilarious piece of Mass Effect fan fiction I read a while ago... "paragon in the streets, renegade in the sheets."
More seriously: Yes. Remember that that one of the (many) reasons for the dom/sub thing is to set aside who are you are at the door. Sure, out there, you're General McAwesomesauce, with all the power and responsibility that goes with it... but in here, that doesn't matter. Kneel.
Fiction is powerful when we can identify with it in some way. Most people that are into the whole BDSM scene aren't in it because they want to be harsh to a slave all the time, or because they want to give up who they are to serve somebody else permanently. Regardless of their personal motivations, it's a temporary deal, and by having the fiction - the story we're crafting here - more accurately reflect what people actually do, we can make for a more compelling tale.
Speaking personally, I'm less interested in a scene when it deviates too far from what I consider to be plausible. That definition is pretty broad - I'm a pretty credulous person, especially when it comes to science fiction - but it needs to have SOME basis in reality or I have a hard time accepting it. People engaging in some BDSM play in the bedroom? I can definitely get behind that. People wanting to turn themselves into a cocksleeve for the rest of their life? That's a little harder to swallow, if you'll pardon the expression, unless their situation is so broken as to make never having to think again an act of mercy.
At which point you have a tragedy, not erotic fiction. Or at least not something I find erotic. But hey, to each his or her own, I suppose.
Also, uh, hi! I'm new here.
/awkward wave