^I don't know why Galaxies looked so vulnerable on screen when up close with smaller ships, the phaser arrays certainly cover 360
edit: The fleet battles are...I don't know what to make of them. I guess fighting at high warp could work, but so could ancient armies run on the horses around enemy cavalry, but chose instead to engage in a cavalry to cavalry skirmishers. I guess the goal is to destroy the other fleet, so they try to do that before conquering other planets.
I also assume that the Breen attack on Earth was of similar nature, high warp attack but they were all destroyed in the end with minimal damage to San Francisco from what we've seen.