The problem is that in HG2 (and in HG1 for that matter) size is strictly a disadvantage except in special circumstances. Size makes you easier to hit, but except in cases where size criticals are relevant, it does not make you any more able to take damage.
That's nothing but TL 15 myopia and a shallow understanding of the rules.
Size does provide an attacker with as much as a +2 To-Hit DM, but only once 20K dTons is reached. Agility, on the other hand, can provide a negative To-Hit DM up to 6. Furthermore, the power plant "densities" at higher TL's make it easier to provide designs with protective agility. So, as sizes grow, ships can also grow more agile.
Size also allows more armor which can reduce critical hits and size prevents the automatic critical hits which result from battery size to ship size over matches. When you remember that critical hits are one of the primary ways ships in
HG2 kill each other, anything that prevents or limits crits becomes important.
Apart from armor, size also helps a ship sustain more damage because more weapons batteries are present.
So, when looking at the
HG2 in it's entirety instead of peering through the
TL 15 keyhole size is almost always a benefit. Almost always because technological advances eventually turn that upside down, just as technological advances always do.
All Traveller ship combat systems except HG, the HG-derived MT system and LBB2 do this differently. Most (TNE:BL, GT, T20, MgT, PP:F, T4?) use size-based hit points of some sort. TNE:BR uses a damage modifier based on factors of 10 of the ship's tonnage.
Size-based hit points are used to speed game play and nothing more. They're also simplistic because they only account for size; i.e. a 40K dTon tanker is tougher than a 20K dTon cruiser because the tanker is bigger.
If you want to give battleships some of their groove back...
... play at lower tech levels.
Especially at TNE's Battle Rider. I only got to play it once, but it looked like a very neat game - except for the (in my eyes) bizarre decision to replace die rolls with card draws and the extreme effects of critical hits.
BR suffers from the same Setting Fluff/Actual Rules dichotomy that the
HG2/
S:9 comparison does. As stated quite plainly in the designer notes,
BR strips down
HG2's combat and damage systems to critical hits only because, given the size of the ships used in
BR, focusing on crits speeds game play.
BR then uses the
same suboptimal designs the setting has been saddled with since at least
S:9.
Battleships don't do better in
BR because the game somehow allows them to do better. Battleships do better in
BR because the game doesn't contain any better designs, designs which the
HG2 rules say should exist.
In history we've seen the title of "Queen of the Seas" pass between design paradigms as technology advances. The same process holds true in
HG2 but we've been blinkered from recognizing that fact for two reasons.
First,
GDW failed to explore their own design rules and, second, the myopic
"Herp Derp battleships and fighters are alwasy best herpity derpity doo" preconception held by too many
Traveller players and GMs.