Interesting. So perhaps Krell should be spelled Q'Rell.I figure Morbius isn't as knowledgeable about the Krell as he imagines himself to be. The Krell may have planned a first step of non-instrumentality but planned further to go full non-physicality becoming some kind of creatures of pure thought and energy. The self destruct was just the clean up device after they transitioned to a higher plane of existence.