In fairness, a lot of the other games use a 2D6 critical chart - you're rolling the exact same number of dice.... if you have differentiate-able dice, you can just treat it as a D66 roll.
There might be something to be said for simplicity, but the problem (or rather a resulting problem) in simplifying is the increase in 'big bad' criticals;
Taking Battlefleet gothic as an example, there are no '4+ to fire' or '-1 dice' penalties - you just have that arc's weapons blown away.
The problem is that - because of the way the rules mechanics are structured - criticals are a lot, lot rarer in Gothic, and generally a lot easier to repair. Loosing one arc's weapons is annoying but tolerable when it's usually only for a turn or two.
Whilst the roll is the same - 1/6th chance each time you suffer damage - a cruiser in gothic has 8 hit points, meaning on average it will suffer only 1 critical in the process of being battered to death. Equally, whilst it needs 6's to repair, it rolls multiple dice (potentially 7 if it's only taken one hit) and makes the attempt in each player turn - twice per game turn.
In A Call To Arms, a G'Quan cruiser with its sixty-plus damage capacity can be expected to suffer about ten critical hits over the course of enough hits to kill it - twice that if under fire from precise weapons - and it can only repair a single critical, on average, every three game turns. Yes, it has access to All hands on deck! but then a depressing proportion of criticals prevent you from using it.
Unless you're going to fundamentally revamp the whole damage model, you need most of the critical hits to be 'mild' ones or else your ship is a floating wreck regardless of its thirty or forty remaining damage - this is the common complaint about big ships in general and narns in particular; critical hits define the game too much, especially since the current ones scale with the ship. A '4+ to fire' on a sunhawk is annoying - a '4+ to fire' on a nemesis destroyer is game-winning.
I'm very much a fan of the redundancy optional rule from powers and principalities for this reason - whilst I lost my last narn-centauri game it more than once kept a G'Quan's weapons operating, which meant that a G'Quan squadron remarkably managed to dismember a big vorchan pack during a single strafing run. Admittedly, they were much too battered afterwards to take on the battlecruiser line and live, but I don't mind that.
Having my units reduced in fighting ability as a game goes on is fine. (I always thought that Gothic's 'crippled' mechanic was simple and elegant)
Losing the ability to control my units movement or attacks is annoying and upsetting because it makes me feel irrelevant to a game's rules mechanics
This is why I suggested greater granularity of weapons in the ship stats - it's easy enough on a ship sheet to note down weapons being blown off as they're hit (like B5 wars, but I'm not suggesting anything as detailed as giving a weapon a damage capacity or armour; just criticals that say lose one, or D3, or D6 weapons from the closest facing). Victory at Sea does this quite nicely with having capital ships having their fore or aft turrets taken out one at a time.
