Lord Byron’s “She Walks in Beauty” is a poem that extols the inner and outer beauty of its unnamed female subject. While this sort of poem was fairly common in the past, we don’t see too much of its kind anymore. This is probably due to shifting attitudes about gender issues and the role of women in society.
One tenet of feminism is that women should be looked at as people in the same way men are, and not as objects—especially not as objects of sexual desire. While “She Walks in Beauty” is not overtly sexual in nature, it does put the female subject on a pedestal that would not be possible for a real human being to live up to.
The poem’s concluding two lines express this unrealistically positive attitude about the female subject:
A mind at peace with all below,
A heart whose love is innocent.
Most women, or even most feminist women, would probably not object too strongly to this poem, because it does not overtly objectify the subject. However, it does look at the woman in a way that is not really possible to live up to. The feminist movement has had to struggle with the problem of male prejudice for such a long time that even a positive portrayal such as this poem can be seen as harmful to women because it does not accept women as ordinary people. They might ask a question like "why can’t we express appreciation for women in general, rather than feeling the need to make them into something that they cannot really be?"