Seriously, this is ridiculous yet you guys are concerned about bridge layouts and ship interiors?
Seriously, I read the 26 pages of mostly you ranting. Do you know what a firing arc is? Are you sure you are firing all weapons or just hitting fire all phasers? Try going into key binds and setting "fire all weapons" to space bar. I have heard very few if any other people mentioning this issue, most are incorrect user error, objects blocking the line of sight etc.....
Provide screenshots to show your settings are correct or fraps a video of your issue. To me, it sounds like user error.
if your using autofire, make sure you have the setting to either toggle - never cancels or maintain. Additionally if your using beam overload, STOP, it has a known issue of occasionally bugging out your cannons.