I'll limit my answer to the RAF and Germany, as I don't know as much about the specifics of Japan to give you a complete answer without any sources in front of me, which is the case as I am on vacation.

Both the Americans and the British had precision bombing doctrines before the war. British planners had the idea of fast, unescorted bombers sweeping over enemy territory and accurately hitting vital enemy production facilities and infrastructure. In short, precision bombing was at first the preferred method of the RAF. However, fighter technology outpaces bomber development in the 1930's, the early daylight raids by the RAF in 1939 and 1940 were so costly that they switched to night operations. They ostensibly continued this precision approach until late 1941 saw the Butt Report, which put together some shocking numbers on just how inaccurate British night bombing was. Essentially, a city was the largest target the RAF could reliably hit at night, and even that was difficult at times. In early 1942, area bombing then emerged as the new principal doctrine, meant to dehouse enemy workers and disrupt morale to bring about an early end to the conflict.

Now, the effectiveness of area bombing in achieving its war aims is contentious. Morality aside, some of the raids were incredibly destructive, and there absolutely were drops in productivity and efficiency after attacks. It's difficult to argue that round-the-clock air attacks, the resulting hardships and privation, and the loss of life did not result in a loss of morale or contribute to the unwillingness of the German public to continue the war. However, the contentious/difficult issue is if this impact was commensurate with the effort, resources, and human cost of the area bombing campaign. For example, I've seen several sources stating that Hamburg's productivity rebounded to ~80% of it's former levels only a few months after the massive area attacks in the summer of 1943. Again, I'm away, so I might be a bit off about the exact %, but you get the idea. The US Strategic Bombing Survey (obviously, some American bias), after the war, pointed out that the effects on civilian morale and satisfaction were not really expressible in an authoritarian police state the same way they would have been in a western Democracy. On the British side, there were many, such as Beaverbrook, who wanted the resources of Bomber command redirected elsewhere based on the poor accuracy and results.

In my opinion, the safest answer is that area bombing did cause Germany some trouble, but it was not the war winner its proponents claimed it to be, and if it was effective, it was as another straw on the camel's back. It is easier, though still debatable, to claim that precision bombing was much more decisive and effective. One also has to look at area bombing through a political context; in late 1941, when the Butt report came out, area bombing was all that the lonely British had going for them in the war. To abandon the only offensive weapon capable of causing Germany the same trouble it was causing Britain might have been politically impossible. There are also diplomatic relations with the USSR to consider- the Soviets were incessantly demanding a second front, and the Americans and British could point to bombing as meaningful contributions they were making towards the soviet war effort. Anyways, those last two were asides, and someone with more detailed knowledge of the politics can provide more information than I can there. Good sources for area bombing in general are Max Hasting's Bomber Command, Richard Overy's War in the air, the US SBS, and Reality and Rhetoric in Air Warfare by Biddle.

Do you mean against ground forces, or do you mean against industrial centers?