Something closer to it has been made this patch, namely Aiodos and most of the people are very excited about that, I will keep things short. Why can't incarnations share our everything, Allods already provided a way to level our reincarnations without doing quests like Time Void. I do not see why our reincarnations shouldn't get to share out world secrets and quest log. I mean of course it would have some issues like 15 level reinc having Tep raid quest if the progenitor has it for instance, but that would give us what is reincarnations all about: leveling. Reincarnations do not and are not supposed to have to do the same quests over and over again (and espicially Path of the Hero ruby) so can we please, please see our reincarnations share our quests and gearscore?
I mean, of course that would eliminate the need of Core Morphers if you have multiple reincarnation slots but it would still lead to a healthier gameplay and also would not ruin a thematically amazing and fun thing for the sake of a single cash shop item. Reincarnation system is good but feels half done and that is bad considering half of our storyline are based of them since 8.0 and that can be a large problem with many people who realized reincs are great.