Paso, I understand what you're saying. It wasn't "utterly senseless," and it no doubt weakened the Wehrmacht to some degree. However, had it not been done, it wouldn't have changed or significantly altered the final outcome. By the time the bombings were in full swing, the Red Army was already in Germany and hadn't had a significant setback in a very long time.
In addition the facilities of military significance (many of which weren't even targeted) could have been knocked out without firebombing the city center, which was the core of the controversy. There was no meaningful attempt to keep from killing civilians, and you are correct that most of that was the work of the RAF, not the US.
To me it's harder to defend than the nuclear attacks on Japan. Those also claimed to be of military significance, but like the Dresden bombings, they primarily damaged enemy morale by terrorizing the civilian population. Nevertheless, the nuclear attacks happened before we set one foot on the Japanese mainland and likely eliminated the need for an invasion, which means it most likely saved far more lives than it ended. That can't be said of the Dresden bombings. The invasions from the East and the West were already in full swing, and the war was almost over.