It is indeed a problem that men reproduce with low quality females. Just imagine voluntary giving your children bad genes. However, that is mostly a result of misandrist feminist propaganda and low testosterone levels among men though. We could probably significantly reduce that problem if we could manage to increase the average testosterone levels among men and spread the blackpill.
If we would legalize rape, that would also make physical strength a more important determinant of valuable genes, rather than height and facial attractiveness, which is the case today (even though they are correlated – tall men, for example, generally have bigger natural muscle masses as well, since they have bigger bodies). A rapist would still have to physically defend himself against the female’s male relatives, possible husband and genetically superior men who do not want him to spread his, relatively more, inferior genes within the womb.
It should also be theoretically possible to gain support among men and high quality females to enslave low quality females, for example by forcing them to participate in the military (they would be too disgusting to hold as rape slaves though), making it impossible for them to reproduce. However, a lot of brainwashing would be needed in order to achieve that, which would require a good elite rule with full ideological control over the mainstream media.
High quality females who refuse to have children should also forcibly be sold as the property to a (preferably rich) man, so she would be forced to spread her genes into the gene pool. Humans need to evolve into a genetically superior species as a whole.