@James,
If you want to see from a realism point-of-view, then yes, space fighters(or 'strike craft' as they are termed in Sins) are rather useless.
They operate in the same medium as their carriers(space), and are only 5.4 times faster(Fighters) or 4 times faster(Bombers). Not ~30 times faster like the F/A-18 Hornet, which is considered a slow fighter. The F-14 Tomcat, before it was retired, was even faster(>Mach 2).
In reality, naval fighters are severely more useful vis-a-vis surface ships because:
1. They're so much faster, obviously, since they move through air and not water.
2. They can carry enough punch, that too, of many different kinds(anti-aircraft missiles, anti-ship missiles, GPS/laser guided bombs, anti-armor missiles, electronic warfare equipment and a close-range cannon).
3. They can see over-the-horizon(see E-2 Hawkeye).
4. They're not easy to kill despite being small because of their maneuverability, their electronic countermeasures(ECM) and because...
5. They're much easier to hide/make stealthy in combat(see F-35C and X-47) than a giant aircraft carrier.
6. The battlefield is the open ocean, not a little gravity well like in Sins.
Thus, the old battleship has been relegated to the role of off-shore artillery, the destroyer and frigate have been railroaded into the role of close-range air defense(like Sins 'flak frigates'), and the cruiser still retains some surface-combat ability. But the surface-combat cruiser is mainly there to go wherever carriers would be an overkill(like anti-pirate operations), and to destroy submarines with their helicopters. Now the title of 'capital ship' is taken up solely by carriers.
But in space, 'fighters' are pointless because:
1. They technically should be nothing more than small spacecraft which accelerate and turn faster. Their engines and fuel load are small, and thus they have no excuse to be faster in top speed either.
2. They are smaller, and can thus carry fewer missiles, or less cooling equipment for lasers. This means longer reload/cool-down times(which is actually shown in Sins).
3. There is no horizon in space(except for maybe a star).
4. They needn't be any stealthier than a larger spacecraft, do they?
5. In Sins particularly, with the exception of the star's gravity well, the battlefield is not any kind of open field but instead is a bunch of closed gravity wells.
6. Even if the space fighter is a drone and doesn't require life support, it still takes 4 times the Delta-v(and hence, 4 times the fuel) of a large missile and is equally susceptible to being shot down. The ~4x fuel is required because it has to take off and reach the target, maneuver to avoid fire, approach and fire it's weapons, and then return to the carrier and be recovered. The big missile only needs to take off and go ram into the target. The fighter's problem can be partially solved by launching it off a large mass driver, but then, the missile can also use the same large mass driver(fictional example being the Novalith Cannon).
Here's a
link to space fighters, and why they actually aren't so useful despite being cool.
