"and I'd have no problem with my kids seeing them. This is in part a reflection on these particular piccies, but also because I don't see nudity as any kind of issue."

How true. These pictures are good and (for want of a better word) 'tasteful'. I don't have a problem with them as such and in fact have pictures of a similar nature on my walls at home, so I have no problem with my kids seeing them either, but I can't speak for every parent. Some parents have some fairly warped ideas of what constitutes porn.

Oh, and they are erotica for the reasons stated elsewhere here. Nudity in an unusual context tends to have that effect.

If the pictures were in colour would you think the same of them?