In terms of sheer practicality, I agree with you, Rodglas. Fighters require more maintenance than unmanned, throwaway missles. If one is defending a relatively stationary target, however (e.g. Babylon 5) then some sort of mobile defensive force could be quite useful. A number of the objections raised were concerning how to get a fighter to and from the enemy; if the enemy can be depended upon to come to you, that should help.
Of course, there are some questions that need to be answered:
1) What is the effective range of your weapon?
2) How is that weapon controlled? Is it completely autonomous, depends entirely upon the mothership, or something in-between?
3) Given the above answers, is there an appreciable communications lag between the weapon and it's control?
4) How is your weapons platform powered and propelled?
And, perhaps the most important question:
5) What's your cash-flow like? What kind of space-borne military craft can you afford to build, crew and maintain?
Given what I read at the link you provided, Rodglas, I have to state that the pinnace is the Honorverse's closest equivalent to a fighter craft. The LAC (Light Attack Craft) does not qualify, and is in fact closer to a miniature starship in its construction; it is designed for protracted deployment, with a power plant and propulsion system rendering it capable of crossing a star system and coming back to its starting point. Being able to harness artificial gravity waves helps in that regard.
This holds true even in later Honor Harrington novels, where massive redesigns occur in LAC construction - treating it more like a fighter, in fact - with some types brought
down to operational periods of seventy two hours.
Given the fire envelopes in the Honorverse, the limits of lightspeed communications become quite apparent - at least, when participating in a missile duel at three light-minutes. Having a less capable sensor package and targeting computer at a closer range is, under such circumstances, a potentially acceptable trade-off. And considering the acceleration rates for a LAC, if you can provide lots of them, the enemy finds himself under a missile or energy barrage at fairly close range, with less time to react and more targets - and their accompanying jammers and decoys - to sort out.
Of course, if you've read Honor of the Queen, then you know that there are ways around the lightspeed limit . . .