He is also largely responsible for delivering a very loyal Legion to Chaos on a plate (Thousand Sons), and banning Librarians which ironically would have been a great weapon against Chaos, in superstitious fear of the power of the Warp. Also, what other primarch dared to walk in into the Eye of Terror? Corax.
Roboute Guilliman for his Tactical Genuine, writing the Codex Astartes and having left behind the paradise of Macragge. His goals were long-term, not so short-term like those of the other Primarchs. Also he left behind the Ultramarines which have one of the purest gene-seeds.
Never will happen, GW did this so you could make you own Space Marine or Chaos Marine chapter without destroying the lore that BL, FW, or GW have created.
Why? That's the allure of them. It adds a depth to the background. Otherwise, you end up going like Star Wars, where they have to explain every little detail and you get abominations like ICS and whatnot.
Yes, but that was the Emperors Orders. Would you be a loyal serverant of the Emperor if you did not follow the commands of the Emperor himself? Who would you be to question him?
It was not only because of the Emperor's orders. The SW had shown their disgust against the Thousand Sons and any kind of psychic users and in the council of Nikaea they were one of the chapters responsible for banning them. The attack ordered by the Emperor (which again was incorrect cause the Emperor believed Horus to be Loyal and Magnus to be a traitor) just topped it off.
The best Primarch was undoubtedly Lorgar of the Imperial Heralds he did everything for the Emperor whatever planet he conquered he left them with the knowledge that Humanity was being watched by Him on Earth I think that if he hadn't of turned the Ultramarines would have been sub par compared to Lorgars loyalty he didn't just love the Emperor as a father but worshiped him as a god and thus he made others do the same
