"Follow it down the rabbit-hole, and the concern about bad book covers traces back to the central issue that, for all recent strides, bullshit stereotypes – harmful stereotypes – still exist. And crap begets crap. What great works can arise if books by women are only sold to an imagined female reader, only interested in "women's things"? If great novels, ambitious and daring, are neutered and forced to compromise or pray for readership on a tiny press? Again: these books do exist. They're just hidden behind ugly covers and cowardly marketing."
from Transgressive Women: How Bad Covers And Sexism Threaten All Of Literature