I think it's incredibly patronizing to say that young women don't see the barriers and that's why they're not voting for Clinton.
In the abstract, I agree. But in practice, I think criticism is both appropriate and compelling. In other words, I believe that there exists some theoretical argument as to why Sanders is better for women, but I simply haven't seen it (and I have seen a metric fuckton of feminist pro-Sanders apologism).
For example, I have seen many, many women, some of whom I know and respect, embrace the claim that Clinton's only qualification is that she has a vagina (a facially misogynistic argument). Or that Clinton's vocal appeal to be the first woman president amounts to nothing more than "vote for me because we share body parts" (ignoring, as misogynists are wont to do, that being a woman encompasses much more than physiology and that representation of women in government is indeed a meaningful and long-standing goal of feminism). I've also seen many make the argument that she represents an old-fashioned, non-intersectional white feminism (an outrageous claim to anyone who knows even an infinitesimal about Clinton's extensive record helping women everywhere from rural Alabama to rural Mongolia). I could go on and on.
If I were to imagine a legitimate feminist argument against Clinton and for Sanders, it would have to be a highly nuanced discussion, a good-faith demonstration that Sanders' positions are so good for women and that Clinton's positions are so bad (a la Sarah Palin) that they outweigh the massive advantage that would come from achieving the major breakthrough of female representation at the highest level of government. Instead of that, every one of the arguments I've heard against Clinton fits into one or more of these categories:
All of these are deserving of the most strident condemnation and criticism.