He did just that in FC, but surely even data wouldn't be able to fight off more than a few in one go. If the Borg have numbers on their side, and let's face it, they usually do, then as soon as Data is perceived to be a threat I'd imagine they'll just swarm him or use some other weapon at their disposal.
1. Because that would be antithetical to what Data believes in, not to mention contrary to the Starfleet ideals he has chosen to uphold. He has ethical subroutines, and more importantly he has ethics, developed not by his creator but by his own judgments of right and wrong through experience with organic beings. Though he may be willing to disable (kill) Borg who are threatening his friends, doing so in a physically violent manner is far more brutal than what he believes in being. 2. Do you remember when he did break a Borg's neck because he got angry they had killed one of his friends? He did not handle it well. It bothered him to no end that he had been capable of such violence, and that some part of him had enjoyed getting revenge for the death of his fellow officer. He would be hesitant to do so again, if not outright unwilling.
1.IMO killing borg who are trying to assimilate the ship he's serving on is justifiable from an ethics standpoint. Locusts once said "Data is obsolete in the new order" so his life is also in jeopardy. 2. This happened because Lore was feeding him negative emotions from the emotion chip.
Borg Drones can adapt, but they can't constantly be adapted to everything. They're the heavy infantry of Star Trek, marching slowly, taking hits, slowly grinding their enemies down. The early Roman Republic, emerging from the previous kingdom, adopted the Greek Phalanx from its earlier cruder formations and formed a strong cohesive heavy infantry. Their neighbors on the Italian peninsula did not have an answer for it, nor the kind of cohesive military to manage their own phalanxi, so they were routinely beaten. But the Phalanx had problems when it encountered other phalanx, or when it met mountainous topography. Rome did not pull a Sparta and just stick with it, but adapted, into the maniple, and later cohort legion systems. These were more adaptable. Each time Rome was beaten it learned from the lesson and adapted. By 53 BC the Romans were knocking on the doors of the East. Their first major engagement with the Parthian Empire at Carrahae was a catastrophic loss. The Romans had had hundreds of years in their territories of heavy infantry ruling the battlefield. The Persians had been beaten by the phalanx centuries earlier and had learned how to get around it. Battles would go back and forth for centuries, but Rome never expanded deep into Persian territory. sorry I digress. The TR-116 was interesting thinking by Starfleet. It wouldn't work repeatedly, but as a sniper weapon (when it doesn't really matter who you shoot, the benefit of drones, no officers), it does allow you to get a few hits in prior to adaptation. An attack on the Borg would seem to need to be using multiple weapon types, in hit and run tactics, outflanking, causing harm, retreating before taking heavy casualties but returning to hit before the Borg could regenerate or regroup.
It is completely justified. Data engages in the disabling (killing) of drones when they are attempting to eliminate the ship. Ending a life being ethically justified, however, does not mean that ending a life in any way is equally justified, nor does it mean that an ethical person would be okay with taking life in any way simply because it was justified. The how is as important as the if when it comes to one's ethical principles. You are correct. He only snapped that Borg's neck because of Lore feeding him negative emotions, which only goes to enforce the idea that he does not feel morally comfortable with breaking his opponent's necks. It is brutal and uncivilized. Even if it were not a matter of principles, however, it would expose Data to more danger than fighting with weaponry, which makes it a matter of tactical intelligence as well. If he were forced to fight physically, I am sure he would do so. But that has never become an issue for him with the Borg except when he snapped the one drone's neck and when he was captured by the Borg in First Contact. In the latter scenario, he did not have the opportunity to fight back, so it does not add or detract to that point. In the first, he did fight back physically, but got angry because of Lore and was more brutal than necessary. So that occasion is questionable and does not go to the point. However, I am sure he would defend himself. It's just never become an issue.
That would be Arthur C Clarke's classic "Superiority", which is available in full here: http://www.mayofamily.com/RLM/txt_Clarke_Superiority.html The gist is that SIDE A attempts to leapfrog the technology of SIDE B, but runs into an unexpected problem - their new weapons are costly and unreliable and take ages to field, during which time they have to cut back on conventional weapons production. Ultimately while they try to iron out the bugs the enemy churns out masses of inferior-but-functional equipment and beats them. It was written in 1953 so I've always wondered if it was an allegory for Nazi Germany's super-weapons, but it might also have been inspired by Robert Watson-Watt's "cult of the imperfect".
Why would breaking of necks be less desirable than burning of holes in chests, though? What Data did to the Borg in most of his hand-to-hand affrays seemed efficient and thus supposedly humane. How, though? Data's unease was specifically for him having felt anger there, and even then mostly for his inability to explain this experience, rather than for the experience itself. Using rayguns is brutal. Data is quite the marksman with his hands, though: he can perform the whole range of actions from humiliating and nonlethal to immediately lethal and presumably painless. We have seen him achieve exactly what he sets out to achieve; with the mutual strangling at the beginning of "Descent", he was ramping up his response on reasonable tactical grounds, not because of his anger. The anger just came on top of that, and scared the bejezus out of him. With the Borg, the opposite seems true: rayguns can be blocked rather quickly by them, but there appear to be endless varieties to hand-to-hand and a general Borg inability or unwillingness to block that mode of fighting. Data is adept at dodging rayguns in a number of episodes. He might do well to close the range and physically disarm his opponents, in almost any fight short of those on open plains devoid of cover. But lightning-fast Matrix fighting isn't his thing, so there are limits to that. Timo Saloniemi