Nice Guy and Nice Gal are idealized gender roles for an optimal society.

I think we're talking past each other here. The "Nice Guy (tm)" phenomenon I was referring to is categorically not an idealized gender role within an optimal or any other society, hence the sarcasm trademark, although it has its roots in (a misinterpretation of) one idealized masculinity. Instead, it's a shorthand way of describing the pathology you described in the ancestor: the guy in question (there are women who do similar things, but the term as I'm using it is tied up in the male gender role) performs passive masculinity really hard and expects that sexual favors will follow. When this fails, usually due to poor socialization and poor understanding of sexual politics, bitterness and frustration ensue.

I actually think the terminology's pretty toxic as such things go, since it tends to be treated as a static attribute of the people so described instead of suggesting solutions to the underlying problems. It's common jargon in these sorts of discussions, though, and denotationally it does describe a real dysfunction, so I'm okay with using it as shorthand. Apologies for any bad assumptions on my part.