you'd be killing multiple decades of built up lore .-. the gene seed doesn't work in a female body, space marines have always been guys, etc. and just saying, the 40k universe isn't necessarily meant to have equality in the various factions :| and as people have said, sisters of battle are the female "space marine" already
You add female space marines to draw in bigger crowds of fans and appeases to the women side too, and also some men enjoy reading about women too (shock! I know! ). But adding female space marines won't break it, just adds more to it.
it breaks it, gene seed isn't meant for the female body :| and again, sisters of battle exist you know
I think difference would be so marginal that there is no point to change working scheme because of that. And about females not breaking already cool lore, well.. There are many opinions
Because unfortunately it opens up a whole barrel of worms. Let's ignore the genetic issues on why females cannot be space marines for the moment. If they were made into them, there would be effectively no difference between either gender. As has been said many times before, beyond somewhat different skeletal structures the process would leave them effectively the same physically. The mental conditioning would do the same, rendering them asexual and they would think along the exact same lines. If this were to happen and stories were written, then critics would pounce on this immediately calling Games Workshop sexist for writing women as being exactly the same as men and demanding further changes. Games Workshop would likely ignore this, digging an even deeper hole for itself in the PR department, or it might accept and it would screw with the setting even further and weaken the overall universe. Things would likely only distablise from there, possibly with Games Workshop trying to force physical changes on the marines or a lot of unnecessary nonsense. None of which would be changes for the better. One of the things it would ultimately harm would be turning every single Black Library book in existance non-canon and forcing major sudden changes to be made to everything from the Horus Heresy onwards. The better option is to have the astartes male and the sororitas female, each with their own strengths and weaknesses. Just give the latter group more stories emphasising upon that with more authors, and retcon every single bloody thing Ward has done to them like retcon their overall numbers until there are more Ultramarines successor marines than their are sororitas.
