Realistic armour is all good and well, but what would a warrior woman with a DD cup (like 90% of women in video games ) do? Full plate would be quite uncomfortable, I imagine.
Well, the average cup size is a B or a C, I believe, and that's increased in recent years (likely due to improved health, nutrition, etc.) So a DD cup is very unlikely, but even then it's a case of boobs go squish. They can easily be bound (i.e. strapped down) to the chest to restrict their movement and to make them appear smaller.
But even if there was some discomfort, all that would need to be done would be to make the chest cavity slightly larger (or to go for a chestpiece that's a bit bigger and wear extra padding), neither of which would really have any negative effect.