I would say that at the time they were good for public morale, it must have felt as a nation we were doing the right thing, also as the enemy it must have played on there minds like, would we get hit or not, .....Using a Tesco phrase...every little helps.....regarding cost of it all, Many things could have been considered as a waste of money....easy to analyze the past now, Interesting point though.
Seems to be focusing on Britain here but flip it around and look at the Germans trying to stave off the strategic bombing offensive. How many Allied bombers were taken out/damaged by ground based flak over the cities compared to German aircraft. The horrendous losses from bomber command and the US Airforce can't all of been from just patrolling German aircraft. But yeah honestly be good to know the ratios if anyone has a good source.
Two further points...
- Dual effectiveness. Again the Germans were probably the first to catch on but if you have a versatile piece of kit that can be effective both shooting upwards and at ground targets you're winning.
- You have to consider the amount of targets you are likely to be up against. Towards the end of the war when the Luftwaffe were virtually out of the picture or at least couldn't maintain sustained operations there was little point having dedicated AA companies. For example, towards the end of the war the Canadians and British redeployed these troops into the hard stretched infantry battalions. Needless to say it wasn't a popular decision among those ranks. They weren't seen as effective since there weren't many of their intended targets left for them to shoot at. The fact they existed all the way through most of 1944 including Normandy would suggest the top brass did see them as effective and essential still at that point.
If this doesn't make sense I'm typing it first thing in the morning after a few drinks.
Hmmmm 90% of bombers reaching their target is a lot differerent from 90% of bombers HITTING their target . (Unless the target was - That city ).
If anti-aircraft defences succeeded in preventing damage to the primary target - whether economic or military they could be seen as a success, even if they didn't DESTROY a single enemy aircraft. If AA forced bombers to fly higher and avaoid certain routes to their targets they would reduce damage and therefore acheive their aim.
I accept that there was probably a positive affect on civilian morale as well which may have been significant (See the Blitz, German civilian morale throughout the war, Japanese morale to the end of the war)