Amanda Marcotte explains why the idea of value free choices in a feminist context can be harmful:

The problem with presenting “choice” as some abstract concept unmoored to social pressures and therefore as beyond critical analysis as the preference of the color of red over blue is that conservatives are happy to exploit that to continue supporting a system where women are systemically underpaid. As this exchange shows, it gives them cover even to push their favorite argument for continuing inequality, which is that the people who aren’t doing as well simply aren’t as worthy. Rachel calls it the “math is hard” argument, and Castellanos basically says, “Yep, that’s my argument.” To unpack that, what’s going on here is the argument from conservatives is that since women are mentally inferior, work outside the home is just harder for their wee female brains, and so they “choose” supposedly easier work that taxes their tender lady nervous systems less. Because of the “I choose my choice” rhetoric, they can bury this essentialist argument about inferior women in the language of “choice”, and it sounds nearly feminist-ish.

Choice in this context has been appropriated by the anti-feminist backlash in the same way “tolerance” has been appropriated by racist douchenozzles, to disguise reactionary bullshit with a bit of fake progressive covering. It works slightly better in this context, mainly because there was an argument to be made that second wave/post-war feminism was too dogmatic in its rejection of the traditional feminine roles of wife/mother/housemaker, which third wave feminism with its emphasis of empowerment and free choice reacted against, inadvertently providing cover to anti-feminist backlash as well.

As Amanda indicates though, while of course you should be careful about criticising individual women for their choices, feminists should always be aware that these choices are still far from free, that they carry consequences. It is therefore right and proper to criticise Ann Romney, not so much for her choice of being a stay at home mother, but more for how she allows herself to be used by those who’d want to see all women being forced into this, as well as for how her simplistic portrayal of mums vs career women carefully erases working mothers.