Explain why we HAD to destroy Dresden.
Everybody in a war thinks they're doing what must be done. Only little children think about war in terms of good guys and bad guys. Of course the Nazis were worse than us, but one must come to terms at the same time with the almost unspeakable savagery we unleashed to stop them.
You're right. The city had no strategic value.
However, we have the luxury of being removed from the situation by time and can look at it through the lens of history. My guess was that the RAF, who did the actual fire bombing, did it out of vengenace.
We just came along later and bombed rubble.