Yes, he has put a "positive" spin on the Dhamma (that doesn't appeal to everyone) but he's also had very direct experience of suffering. Perhaps he felt this approach was needed, and then when many people in the West responded positively (he was nominated for a Noble Peace Prize) he took that as a message that what he was saying and doing, his ideas and way of presentation, was something helpful to others.
Short account of his background here, from TIME magazine...
Thich Nhat Hanh: The suffering of the Vietnam War
"Few battlefields were as bloody as Vietnam, where France and then the U.S. fought nationalists and communists for more than three decades. Though part of a quietist tradition, Nhat Hanh couldn't help being drawn into the conflicts around him. He could see how urgent it was to assert the buddhistic importance of compassion in a culture growing increasingly violent. War, he believed, could be ended only by extinguishing the emotions—fear, anger, contempt, vengefulness—that fueled it.
In 1965, after yet another Buddhist self-immolation, Nhat Hanh wrote to the American civil-rights leader Martin Luther King Jr. that "the monks who burned themselves did not aim at the death of the oppressors, but only at a change in their policy. Their enemies are not man. They are intolerance, fanaticism, dictatorship, cupidity, hatred and discrimination, which lie within the heart of man." Nhat Hanh led King, and, by extension, American public sentiment, to oppose the fighting in Vietnam. During the late 1960s, while living in the U.S. in exile, Nhat Hanh became one of the icons of the antiwar movement. His essays were published in such leading periodicals as the New York Review of Books, and his poems were sung, like songs of protest, to guitar accompaniment at college campuses. It's no exaggeration to say that Nhat Hanh helped force Washington's eventual withdrawal from Vietnam.
Nhat Hanh, now 80 years old and living in a monastery in France, has played an important role in the transmission of an Asian spiritual tradition to the modern, largely secular West. "Do not," he has written, "be bound to any doctrine, theory or ideology, even Buddhist ones. All systems of thought are guiding means, not absolute truth."