Simmer down there dude, take in a deep breathe you'll be ok. This has been a long standing problem with this sim and frankly more than likely will be for other new sims in the future for a while as Blackdog_kt has pointed out. Most of us have just reclunctly accepted it and moved on still enjoying the sim, it sounds like you are a new comer to the world of 1946. The only major beef I had with the gunners is they can get you from angles that are impossible to shoot at unless you are physically holding the MG out of the a/c and aiming. This is usually seen in the dive bombers but still, I just have to keep moving and don't sit in one place. Though I have noticed myself, not sure if others have noticed this as well but when coming straight down on a bomber the gunners usually don't do much, not sure maybe they are just giving up and accepting whats coming to them.
In any case don't let that ruin your enjoyment of the sim, go download some mods, create a campaign, join a online squad ect just enjoy it for what it is and try to realize its not perfect as no game is and if anything leave it at that.
Flyingbullseye