My main argument in nudity is that if a scene logically calls for nudity, it should have it and they shouldn't shy away from it. If they want to avoid explicit nudity, they can do so with creative camera angles as previously mentioned, but it still needs to make sense.
In Origins, the sex scenes where they're in their underwear are stupid and awkward, but in Morrigan's case, they're absolutely bizarre, because you can clearly see in her default outfit that she doesn't wear a bra, so now the implication is that once she takes off her standard robes, she puts a bra on to have sex.
In Return to Ostagar, you have Cailen crucified, hanging up there completely stripped of his armor, but the darkspawn left his loincloth thing on to preserve his dignity. No sense.
In ME3, you have the scene with Samantha where she's showering in her bra and panties, and Shepard joins her fully clothed. That makes no sense.
So my point is that if you've written a scene where it doesn't make sense for all parties to be clothed, don't have them be clothed. That simple. It's not a matter of fan service, it's not a matter of equivalent exchange, it's a matter of logic.
It's also a point that while I'm not demanding nudity, I do think that there's a problem when they don't have a problem showing things like the broodmothers and especially the Mother, who have six to eight ****** flopping about to disgust us, but are unable or unwilling to show nudity in a positive light. I think that really says something about our society and our perception of the human body when we say that showing nudity for the purpose of shock value and grotesqueness is perfectly fine, but showing it for consensual, loving sex scenes is beyond the pale, apparently.