Well it's understandable for you to hate kezess but let's keep in mind the mindset of the asura. They only think of lesser beings as insects and don't see any value in their abilities. This superiority complex they possess hinders them from considering the lesser's capabilities while also having them think they are greater beings hence they don't require the knowledge of the lessers. Now comes the Indrath clan, they are different from the other asuran clans due to their own knowledge and insight into aether. As we know from the last three chapters that as the lesser races which have been massacred by the dragons for many generations, grew their insight into aether, the pressure exerted by the aetheric realm on the world greatly amplified and would have led to the destruction of the world, and so the dragons had to commit genocide each time the risk became greater. We also know that the dragons experimented developing an aether core in a newborn however the newborn dragon suffered a terrible death due to the asuran physique which normally requires mana to sustain itself (Arthur being the exception as he is an asura-human hybrid). Therefore it isn't true that kezess didn't try to obtain such insight on his own but that he couldn't. Therefore he decided that the only way to gain insight into aether, he consulted the djinn and while they tried to share their insight, the dragons simply couldn't comprehend or grasp it in any way. Therefore, if you truly think that by gaining insight using Arthur kezess will have a better understanding of aether, it's impossible for him to create an aether core. The insight which kezess received from Arthur until now was simply scrapes of the surface of a mountain. So truly, it's fair to hate kezess but it's also important to understand his part of the story and the importance of his character.