Why is intelligence important for the Receiver of Memory to have in The Giver?

We can see why intelligence is an important quality for the Receiver by examining how Jonas uses his intelligence as the Receiver.
One reason why the Receiver might need intelligence is because the Receiver is learning about things that do not currently exist. The concept of color is an example. Jonas notices that there is something different about Fiona's hair, but he has difficulty describing it because he has no concept of color, until the Giver helps him see through transmitting memories. I think that Jonas's intelligence makes him more open to learning about new concepts such as color and feelings.
While the Receiver learns about these new concepts, they are not allowed to discuss them with others. Jonas must communicate with those around him without giving away what he's learned. I think intelligence is a good trait to have so the Receiver knows what language to use when talking to others who do not understand concepts beyond Sameness.

Intelligence is an important skill to possess as the community's Receiver of Memory because the Receiver of Memory must exercise their knowledge when the Committee of Elders consults them regarding a significant decision or change in policy. The Giver explains to Jonas how the Committee of Elders once sought his advice about increasing the rate of births in order to have more Laborers. Fortunately, the Giver was intelligent enough to articulate the dangers regarding overpopulation, which would result in hunger, starvation, and war. Having the intelligence to discern when possible political decisions could be dangerous is an important skill that the Receiver of Memory must possess.
The Receiver of Memory must also have the intelligence to recognize how past events affect the current conditions in the community. Understanding the nuances of each decision made to create a comfortable, structured, safe community requires intelligence.