Geeb,
I realise this will upset you, but there are other bombers. The B17 was a numbers-operator. I'm kinda amused at you saying 3 b17s could close a field before. You could pretty much do the job with 1 lanc before.
The B17 is a weapon of choice. Depending on arena conditions, how long you want the flight to take and number of planes available, you can still put it to good work if you need to focus on the defensive aspect of your vehicle rather than payload.
IF you need payload, then you fly the Lancaster, and risk the decreased defensive armaments.
The Lanc and B17 weren't front-line fighting machines. They were used for advanced softening of targets, or attacks on behind-front-lines targets.
Hopefully buff pilots like myself will begin planning operations more strategically, putting missions up and diverting some of the country's player resources to operational tactics. The result is that this absorbs the growing player base by encouraging players to spread out a little - there are plenty of us now that we can afford to be fighting two fronts. A fighter/jabo furball at the front combat fields, and tactical bomber raids further behind.
There ARE plenty of pilots who WANT to fly bomber escort in this game, but a solo p51 flying escort for a solo lanc is kinda dull and disintersting.
Try knocking up missions on the mission roster. I find that I get my fighter slots before I get my bomber slots filled. Pilots get as much fun from defending their friendly-buffs as they do from killing an enemy one - because they know the adrenaline rush their oncoming enemy is having

It's a furball with a motive on BOTH sides.
As to citing the B17 as proof that bombers are now useless...
Take the example of RAF 617 Squadron - the Dambusters. What aircraft did they fly? Bet your answer is: The Lancaster. Actually, no, most of their sorties were flown in the Mosquito performing precision bombing or pathfinder-marking jobs. However they also flew a variety of other aircraft as the need required. They even flew their share of Wellingtons.