I do not find the nudity necessary, and at least with Bioware games in the scenes I have seen, it has not been excessive. But not all games are this way, and as mentioned, Bioware games have become more relaxed almost with each new title. The slippery slope for me is when it reaches the point where I must pass on these titles as well as the others, and I am for ideas as suggested by the OP to help stop this from happening.
We can argue about the 'necessity' of nudity for a while. If we're talking about 'necessity', all we needed was pong. Video games could have stopped there and we'd have had all we needed.
I believe, adamantly, that nudity has artistic value. It can be used to show comfort, vulnerability, intimacy, passion, and savagery. There are scenes Bioware has done that should have included nudity.
The one scene I always point out is Samantha's romance scene in ME3 where she's showering in her bra and panties, and Shepard joins her in the shower fully clothed, and then afterwards their cuddled together in their underwear. Everything about that scene is wrong, to me. Samantha should be naked in the shower because that's how people shower. Shepard should slip out of her clothes before joining her because that's what you do in that situation. Afterwards, could go either way, but it's just my personal experience that post-sex cuddling doesn't happen with the clothes on.
The whole scene could have been a very passionate, romantic affair. Instead it comes off as absurd, hilarious, and artificial in the ways they avoided showing nudity in a situation where there was no logical reason for the people involved not to be naked.
There are other scenes like this scattered throughout both series, but that was always the most blatant example to me.
And ultimately that's my thing; if they write a scene where it makes more sense for the characters to be naked than clothed, then they should be naked. Logic should not be defied for the sole, artificial purpose of shielding our eyes from nipples.
You can say you'd rather just avoid they show those scenes all together, which is fine, I guess. But honestly the pure fade to black really has it's logistical issues, too. There are romance scenes in The Old Republic(which is restricted by the T-rating) that have two people flirting, then kissing in one room before walking off to another room to have sex before getting dressed and walking back to the room they started in before speaking to one another again. The very fact that I actually thought about the mechanics of this where these two people had sex and just awkwardly avoided looking at each other in silence as they got dressed, and had to leave the room they had just made love in before being able to carry out a conversation shows how immersion breaking the whole thing is.
At least for me.