Was messing around with full air strat last night and this happened. I was taking mexes across the map and keeping resources at low negatives, and putting full resources otherwise into bombers for the entire first 15-20 minutes. I had a ridiculous number of t1 bombers, and they all died in about 2 seconds to a small handful of t2 fighters before dropping even 1 bomb on the tanks below. This felt really unbalanced. edit: I see that in the gamma patch notes the t2 fighters got a 50% aoe nerf and 2x mass cost so maybe that'll be enough (the aoe decrease). It was just pretty broken how useless t1 bombers were against a small # of t2 fighters. He could have maybe even just had 1 fighter.
Also, the ground AA (bots, vehicles and turrets) seems to have been buffed, so that should help too. Time to get playing to find out for sure!
There is no reason whatsoever to build T1 bombers for any purpose. They cannot do anything other than die. They would lose to a wall section in a straight fight. Ten of them can't take a single mex out if they tried. Save your metal, rush to T2. T1 fighters are acceptable in small numbers before you can get T2 out.
There is a very good purpose to build them, I do so every 1v1 game. That purpose is to kill your foes fabrication bots early game (3->7 min in). This is actually quite a big win and will mess up your enemies expansion and base building. later in game they are pointless but in early game they are extremely good at frication bot sniping, and stopping early raids.