Why is it that in so much sci-fi, you have massive war ships with miniature turrets in comparison to the frame of the hull??

Sure, I get the idea of point defence... But what are you defending exactly? The Enterprise for instance - is basically a flying hotel. However a warship... shouldn't that be built around its primary function, destruction?

Is it because a ship's too big and thus, **automatically condemned to poor rates of pitch, yaw and roll?** In a universe in which life and death may depend on you being able to align out and manoeuvre into a position to FTL; or give one side of your armour a chance to re-solidify after a period of concentrated fire. Is it too hard to imagine ships of all sizes having sufficient agility to just "do shit"; as without the hindrance of friction, moment is the only factor affecting the ability to set heading and bear aim?

It's akin to a tank, with shopping trolley wheels and hand guns attached to the sides of the hull. Sure, APCs are basically armoured cars with tiny guns attached to the chassis to protect the cargo "in case shit" - however, their mission critical goal isn't to destroy.

If you're building a warship (let's assume it's one with a tech-level high enough for the automation of most tasks), why have a crew of hundreds or even dozens? Why create so much baggage for yourself when in reality you need only be a massive, armoured, flying gun, with engines and a few counter measures flanked by smaller, armoured, flying guns designed specifically to take out and disable ships of its size class and above?

Imagine if you will, a universe where warships momentarily skate the surface of suns. A time where their tools consume more energy in minutes than has ever been generated by mankind in all of history. Where metal has been bent and engines bolted to the sides of weapons, with room nil for all else but courage and will... ...

If we ever got to that point, turrets would look kinda silly, surely?