I think we're hitting on a difference in design intent here.
I always like looking at real-world naval vessels when drawing comparisons, so let's have a peek at any given battleship versus any given aircraft carrier. I'm not sure if you guys have noticed, but even though the battleships have enormous guns and would clearly win in a direct engagement, aircraft carriers have totally obsoleted battleships. Why? Coupling reconnaisance (from patroling aircraft from the carrier or other ships in the area) and radar, it isn't necessary for the carrier to enter the battleship's range. It's tempting to say that replacing big guns with huge missile batteries, but missile systems are compact enough to be placed on smaller warships (i.e. destroyers), so there's really no need for some huge, hulking craft designed for direct engagement.
In FreeSpace, as fighter and bomber technology continues to improve, I foresee decreasing emphasis being placed on direct firepower, in favor of additional fighter and bomber capacity.
Just for giggles, let's consider a wargame scenario, where an Orion and a Hecate enter opposite sides of a star system. Assuming the ratio of escort fighter to recon craft to bomber are kept the same, the Hecate has 50% more recon fighters to deploy, meaning that they are quite likely to spot the Orion first, but let's suppose that they receive word about each other at exactly the same time. Immediately, the Orion starts to either launch bombers or fighters, depending on whether they want to start on offense or defense. On the other side of the system, the Hecate, having greater launch capacity begins launching bombers and escort fighters. In addition to its superior anti-fighter armaments, the Hecate will have escort fighters in position by the time the Orion's bombers arrive. The Orion, on the other hand, is going to have warheads sticking out of its hull in very short order. (You could argue, here, that the Orion could choose to launch fighters before bombers, but they're unlikely to match the Hecate's ability to launch escort fighters, and they're going to have zero capacity to attack the Hecate, and if you can't get on the offensive, you can't win a fight.)
You might posit that the Orion could try jumping to the Hecate's location to turn the tables, but once again, superior fighter and bomber forces are going to win the day, as the Orion is going to be neutered in mere minutes. What's more, by the time an Orion is capable of jumping to the Hecate's position, the Hecate can jump to a new location, and then we're back to square one. Even with big, flippin' beams becoming standard equipment on large warships, the universe is becoming a fighter/bomber pilot's paradise.
The issue of corvettes came up, and again, I refer to real-world navies. Removing fighters from the equation, even with a two-inch gun and some kind of lightwieght surface-to-surface missile system, in a direct engagement, a naval destroyer is going to kick the crap out of an aircraft carrier. Current weapon systems are just ridiculously powerful, and there's not really an armoring technique that's both viable and effective. Seriously, if you double a carrier's weight just adding armor plating to it, so that it can take multiple hits from surface-to-surface missiles, all you're likely to do is save your enemy the trouble of sinking your carrier.
Likewise, there's not a really good defense against beam cannons, if you actually put yourself in a position to be fired upon by one, so as a warship's commander, your goal is to avoid being put in such a position, while directing fighters and bombers toward your target or pursuer. While I'm no expert on the subject, I'm pretty sure that the number of direct naval engagements has been steadily declining on a per-conflict basis since World War II, where aircraft really started to play a significant role in naval combat. Naval destroyers exist both to provide support for ground forces and to keep submarines away from carriers and other strategic targets.
In the FreeSpace universe, I see technology moving space combat into a realm even closer present-day naval combat. I see the TAG missile system being used to allow corvettes to target enemy vessels from ridiculously long range, allowing fighters to take over a bomber's role in a pinch. I foresee the destroyer class, as defined by the Orion and Typhon being phased out entirely, in favor of a dedicated carrier class, while corvettes move into a defense and long-range support role. As hinted at in the Deimos' tech room entry, I doubt that cruisers will have a role in the future of FreeSpace, unless they can integrate some type of stealth technology that isn't viable for ships any larger than cruiser-class. Even at that, though, since first-generation TAG technology can overcome stealth tech, I think cruisers are just dead.
Anyway, all that chat about the Hecate and Orion are nice, but the three BVas beams on the Hatshepsut make a stronger broadside than the Orion has (which mixes BGreens and TerSlash beams), and its fighter compliment is comparable to a Hecate. All told, I think that if Admiral Khafre and Admiral Petrach had a showdown, it'd start with Khafre stating something along the lines of, "Bite my well-tanned, exoskeletal ass," and it will end with appropriate results to back up the smack talk. Vasudans have superior equipment, and though it'd take an autopsy to find them, they've probably got positively massive testicles, which can provide Samuel L. Jackson levels of badass to even the average Vasudan.
I'm pretty sure I had more to say about this, but it's late, and even if all these Orion-loving junkies saw enlightenment, the forum script won't let them change their votes anyway. I've also probably said too much by the time I get to the vasudan-anatomy imagry.