Because the flak won't kill the bombers, the bombers WILL kill the CV, then who cares if you intercept them or not?
You want realism? Make 88 gunners have to move to the fusing station to change the altitude on their shell bursts, make 88's, 5", and field guns hit friendly aircraft... the absurdity is that it's computer controlled, it one shots fighters, and it's not even projectile based (i.e., watch an 88 fire, you can see the shell) - it just "happens".
I have been shot down twice by Enemy CV fleet. Not because I was trying to hit them, just by being in the wrong place at the wrong time.
I was caught by surpised not knowing they were below me. The 1st time I was shot down I was at 17k, the 2nd time I was at 20k. So do not
say they do not shoot down Bombers. About the 88's and the other guns hitting friendly fighter or aircraft, don't fly in to it. Thats why the German Pilots
waited till the Bombers flew out of the flak fields, then they attacked. As for Fleet defending, then be carefull when you intercept enemy bombers or
enemy aircraft attacking your fleet.