1) A squishy human being that blacks out if you burn too hard. (MAGICK! prevents this ^^)
2) Engines and enough fuel to reverse your delta V after an attack run and come home, plus fuel to maneuver and get there in the first place. (u sure the engines use fuel?)
3) Life support for your squishy human. (sure but who knows maby it will fit in match box ;3)
4) Heads up displays to interpret data for your squishy human. (actually whole cockbit with chairs and stuff...)
5) Warheads and propulsion for your warheads, assorted weapons systems. (indeed fighter needs guns)
6) Complicated mechanisms back at the mothership for retrieving your fighter. (jup carrier is needed for fighters)
7) Crews of people to repair and rearm your fighters. (or some automated system...)
8 ) Room and life support for your pilots on the mothership.
9) Gym facilities to keep your pilots healthy enough to survive the meager number of Gs they can resist already.
Now lemme make a list of the things a missile needs.
1) Engines and enough fuel to get there and maneuver.
2) A warhead.
3) Guidance systems.
The less things you need, the more mass you can devote to engines, complicated guidance systems, or a more powerful warhead. If you're worried about your missile not being creative enough, then you need to get a better programmer, or if you're fussy, use a laser to command it.
but on the other hand its hard to rearm missiles... and that squishy human in the fighter can make desicions unlike long range missiles... by ur logic there wouldnt be single fighter still in service by any military but look and behold... theres plenty :3 jup missiles are cheaper than fighters... but on the other hand u need battleship to launch em from and those are mighty expensive considering one hit can take em out...
and yes all this is completely theory cause no one can prove what tech we might have at the point when war in space becomes an actual issue