Yougotbale
Objectification, choice, exploitation and social roles are separate but connected concepts which have feminist as well as more general political and philosophical implications.
Wikipedia is useful to get the basic concepts of objectification:
Objectification generally: en.wikipedia.org/wiki/Objectification
Sexual objectification: en.wikipedia.org/wiki/Sexual_objectification
It is also important to think about these issues at a personal and a class level. A person may be objectified on an individual level and this may or may not reinforce the objectification of a class of persons. The issue of choice is not relevant to the issue of objectification (although they may overlap). Images of semi-naked men could objectify an individual man but in our society, the picture would not contribute to the objectification of men as a class because men as a class in our society are not pigeonholed as the decorative sex class. (I'm meh about pictures of men; if men are concerned that there is a move towards men being relegated to the decorative sex class or object to individual objectification then by all means, they can object to those pictures.) Similarly not all naked pictures of women objectify either the individual woman nor contribute to the objectification of women as a class (e.g. the non-sexual athletes' photos).
A picture of a person reinforcing a social role is not necessarily objectification although feminists might object to it for reinforcing a social role if it suggests that the role is innate.
AutumnMadness the pictures from my link are not, in my view objectifying the subjects, other than the women in the sexy poses. The subjects are well-known athletes who are being celebrated for their achievements, pictured in athletic poses, they are not interchangeable. I don't agree the question is about beauty.
Yougotbale if women were liberated from oppression (this is not the same as equality or roles being the same), there could still be objectification at an individual level but this would not contribute to the subjugation of women which is partially achieved by women as a class being reduced to being the decorative sex.
Looking at choice, no-one has said these women did not choose to do this freely. Their choices were, of course, influenced by society's norms and values, as our choices often are. I'm not really concerned about the issue of their individual choice in this case. I would agree that these women and women generally can make a free choice to be objectified at an individual level. They can't choose how these pictures will contribute to the continued objectification of women as a class, that is at the societal level and not within their control.
As individuals, we help to shape society in the choices we make and we can change our society by our choices. For example, casual racist comments have declined enormously over the past 30 years. One factor in that has been individuals choosing to disapprove of racist comments by others and choosing not to make racist comments themselves. A black actor portraying a character imbued with unreconstructed and unexamined racist stereotypes could be making a free choice to do so but this choice would negatively reinforce racist stereotypes. A woman making a choice which contributes to the continued objectification of women as a decorative sex class is not making a feminist choice.
Sorry for the screed.