Serenity, what good is the bomb load if the platform can't get it to target?
Historically these planes were DOGMEAT to even a few fighters. In this game they can literally outfly all but the fastest planes, outgun every plane (I've seen instant kills from bombers on every plane in the game, no matter how heavy the attacking fighter's weaponry was).
The bombs are not an issue. The issue is that the bombers fly full throttle 100% of the time, climbing faster than they ever did historically, levelling faster, outruning fighters faster than they ever did historically, and on top of that this super-speed compounds existing problems with the lethal guns setup. (Guns would be fine if the plane wasn't moving 2x historical cruising speeds, but as-is they reduce all planes to sitting in tail chase, making them easy targets).
It's not the bombs. A B-25 carries the same 1k bomb as a B-26, as the Ju88, as the B-17, B-24, and Lanc.
The difference is that the bigger bombers are faster, much better defended, and will get to the target and drop the ord more than light bombers will.
Lanc isn't as well defended, but it's buggy-as-hell to kill and still quite survivable.