This is not about Classic Traveller, so it's rules are only slightly important here, and only where they differ from Mongoose Traveller do they get brought up. I haven't gotten to High Guard yet, so the difference between it and CT High Guard combat hasn't been a subject, yet.
Yes, I know Fighters in Traveller is flame bait subject, but I'm going to look at it any way.
I agree, 10 dTon fighters are damn close to useless, other than against smaller (say sub 400 dTon or so) and lightly armored space ships. No arguments there. On the other hand, I think a 50 dTon Honor Harrington style LAC can be made that will as difficult to damage with non "capital" weapons (read a bay weapons or bigger) and that will be a threat, if only for a single volley or so, against major ships (i.e. not another small craft), A 50 dTon LAC style craft could carry, for example 1 Torpedo and one laser (for use as point defense or vs smaller targets), which would make it a threat, if only for a single volley, against most ships. A basic non-nuke torpedo does 4d6 damage, which, is going to penetrate most armor on an average roll, and all armor on a just slightly over average roll, just using rules as written.
Page 99 of High Guard has a 40 dTon, armor 10, 10G torpedo boat that carries 2 torpedoes. It's fairly close to the HH style LAC as it stands, but isn't self escorting and can be hurt by a laser or a missile. Maybe. If they roll real high on damage.
Armor is very important in space combat in Mongoose Traveller and is fairly cheap, both in tonnage and credits. With Rules As Written, 6 points of armor makes you invulnerable to a pulse lasers (or beam lasers if you apply the High Guard changes) and 12 points makes you beam laser (or a pulse laser with HG changes)1 lasers proof. Not going to stop a Particle Beam or a Meson weapon, but you are using turret sized lasers and non-nuke missile? I laugh at you and call you a silly person.
In MTU, I use the personal level combat rule that the effect of the to hit roll (the amount over 8 rolled, after modifiers) is applied as damage on that attack. Any effect over 6 means that 1 point of damage gets through, regardless of armor. This makes good and lucky (defined as skill level 4 and rolling a to hit of 12) gunner gets +8 damage, which against an armor 6 craft is going to do at least 3 points of damage and could do 8, assuming it's only a 1d6 weapon, which translate to either 1 single hit, or 2 single hits, which, could, in theory, blow a fighter out of space. On the other hand, if you roll a 7 on location both times, all you did was reduce the armor by a total of 2 points. Of course that will make the next hit do more damage. You want 6's or 8's if you want to kill it. Other non 7 results will result in possible "mission kills" I'll grant, but not that expanding ball of plasma.
As my project for the day, during breaks from "Project Clean the House" I am going to design a 50 dTon LAC that is "self escorting", an 30 dTon torpedo boat (which might no be as easy, despite 30 dTon being a sweet spot in small craft design and a 2,000 dTon 4G Jump 3 ship. The 2K ton ship would be a "Light Cruiser" in a Large Ship Traveller game, but would be a "Battle Ship" in a Small Ship Traveller game.
My Traveller Universe is a "Small Ship" game. Capital (i.e. ships over 2Ktons) are very, very rare, even in the Imperial Navy. Mongoose Traveller's "Barrage" based combat doesn't make this a bad as it could be. Granted it does eliminate spinal weapons, but a "large bay" comes damn close for a smaller ship. Not having capital ships also cuts down on the 9 to 37 (!) pages of tiny type ship's maps.
- Rant. Mongoose needs to stop doing that. The maps, for large ships, are too small to read and damn near useless for a 'dungeon' map, and in some books, just plain ugly due to the software used to draw them. Waste of book pages, In My Arrogant Opinion
1They reversed which one does 1d6 vs 2d6 in High Guard, but made pulse lasers have a -2 DM to hit. Why? I don't freaking know.