EXACTLY !!
Speer himself commented that one of the biggest effects of the bombing campaign was drawing off 75% of 88mm gun production for (largely ineffective) air defence. Go ask any Russian soldier (and, after D-Day, later Western European) how much they would have liked the Germans to have 4x as many 88mm guns as they actually faced.
The loss of Luftwaffe pilots was especially important on the Eastern Front, where the largely inexperienced Russian aircrew were shot down in droves by the better German pilots (Erich Hartmann - 352 kills, all but 7 against the Soviets. Gerhard Barkhorn flew throughout the Battles of France and Britain without getting a single kill,but then shot down 301 Soviet aircraft). Thanks to Bomber Command, they weren't very many of them.
Another point rarely mentioned about German productivity was that for most of the war, the Germans were much less productive than the Allies. Women were rarely used, for example. The increasing production figures need to be compared to what could have been achieved had Bomber Command not been hard at work.
Interesting article here describing how the German production miracle in ww2 was largely due to measures introduced just before the war, coupled with economic measures introduced in 1942 (such as a wholesale switch from cost-plus to fixed-price contracts.), and the production of factories in the Occupied Territories (e.g. Poland)
http://www.econ.yale.edu/growth_pdf/cdp905.pdf
It points out that the major bottlenecks in German production were due to
a lack of labour, and the
ineffectiveness of labour working outside their home town. Both of these factors are directly related to the Area Bombing campaign.
Try this for an idea of the effects of the bombing campaign
The next sudden about-turn of its production program again coincided with a
considerable loss of efficiency. In 1942, Heinkel had to give up its production of Ju 88
wings and started to fabricate the new bomber type He 177. As a result of this change
the “regular” depreciation rate of Heinkel’s capital stock soared to 28 % in 1942/43. This
time the necessary adaptation process was made even more difficult by the fact that
simultaneously a large number of concentration camp prisoners newly arrived at the firm
who had to be trained and made further adjustments of the firm’s organization of
production necessary. It took another two years until Heinkel was suddenly ordered to
stop the production of the bomber He 177 and to concentrate instead on the final
assembly of the fighter Fw 190 which was needed to repel the Allied bombers.
You don't have access to local labour (workers killed and bombed out of their homes)
You lose huge amounts of efficiency importing foreign/slave labour.
Just when you get them trained,you have to switch to building fighters to defend against the bombers.
I think research in the next few years will continue to show just how effective the Area Bombing campaign was.