[Stormcrow]

In Tolkien, elves are primarily motivated by their desire to further glorify the creation of Iluvatar. That's Art. One way they create Art is by their offspring. Elves don't have children because their instincts tell them to procreate; they have children because they've found the ideal time in their immortal lives to create a work of Art. This is why elves don't overpopulate everyone else out of existence.