Skynet is the evil artificial intelligence behind all of the Terminator movies, and its first priority is to kill all humans. After the program took control of the world's supply of nuclear weapons, it used them to blow up a good portion of the human race. What was left of humanity lived on, only to fight a near-invincible army of merciless robots with whatever used, battered and broken weaponry it could scavenge. And yet, not only did this one-sided war "span over 30 years," instead of the more expected "one really shitty afternoon," but human beings actually won out in the end. Do you know why? Because Terminators were the worst idea in history. Here are all the reasons they suck:
There are many varieties of robot in the Terminator universe, but all of the titular Terminator models are vaguely humanoid machines, some of which are coated in flesh so they could pass for people. This was so they could better infiltrate the human resistance camps and kill all combatants once inside. They were given living flesh because rubber skin just didn't look right and sparse personalities so they could make it past the gate guards. And they were made anatomically correct, because they might need to infiltrate the camp showers and possibly bone a few of the resistance fighters to lower morale before the slaughter started.
Wait, how does that lower anything?
But why bother with any of that? Skynet's main problem wasn't that the robots couldn't get past the velvet ropes at all the human clubs because they looked too roboty; it was that Skynet couldn't find where the damn humans were hiding in the first place. If it knew where they were, Skynet could just send over one of those tanks that shoots out motorcycles, or a jet with giant blades, or hell -- maybe just a good old-fashioned bomb, if it's feeling a bit boring that day.
The whole resistance movement revolved around hiding from Skynet, not just locking the doors when Skynet came knocking. Saying you needed human-looking Terminators to kill humans is like saying the reason we haven't killed Bin Laden yet is because our soldiers don't have convincing-enough turbans to get into his cave. Whatever the motive, the one thing we can establish for certain is that, although Skynet is fully capable of making gigantic aircraft and heavily armored tanks like these ...
... it prefers to make robots that look and behave exactly like people instead. So ... they're for intelligence-gathering, right? The Terminators are the espionage models, and all the battlefield robots look like those bitchin' death machines above. Except ...
... they don't. Several times we're shown that the skinless, humanoid Terminators are the main Skynet force on the battlefield. These are the foot soldiers. Skynet's version of infantry.
What's so wrong with that? Well ...
So we've established there's no great reason for the espionage, and that the Terminators -- modeled after humans, remember -- are mostly used in battle as foot soldiers. Humans are at the top of the food chain because of our intelligence, community and opposable thumbs, not the rest of our bodies. We don't exactly have the best design in the animal kingdom. In fact, you know what's better than us?
Those fingernails will fuck your day.
Literally everything: Four-legged mammals run faster and jump higher, winged creatures take to the air, clawed creatures burrow beneath the earth, finned creatures swim -- a warrior robot simply has no need for hands or bipedal locomotion. These things aren't pre-existing; Skynet's designing and building new ones all the time, expressly for the purpose of killing folks. The robots don't need thumbs to grab guns; guns could just be built already on them. Or if you do find humanity's one physical advantage -- our hands -- to be a necessary feature, why copy the rest? Just slap some humanoid arms on a giant land shark! Copying humanity's schematics presents no discernible advantage on the battlefield.
Unless Skynet understands our biggest weakness is boners.
But Skynet stuck with the most accurate human design possible -- no six-armed humans, no humans with jetpacks -- just an ordinary human shape. Which means the Terminators have to walk everywhere they go (and they are shown doing just that in the films) while their supersonic jet robots and tank-treaded death machines hover around, babysitting the poorly designed foot soldiers.
"Guys, wait up! Carl twisted his robot ankle and chipped one of his metal teeth that we have for some reason."
Oh, but it's so easy to be snarky and tear ideas down. It's so much harder to build. Hell, it's not like we've got better human eradication tactics just sitting around.
Wait -- yes we do. We use them all the time. In the goddamn Army.
For example, much like the Terminators, our armed forces use flying drones. But unlike these advanced killer robots from the future, designed and given life by a vast, incomprehensible super-intelligence, we thought to give ours guns: In Terminator Salvation, a drone flies up to young Kyle Reese, identifies him and then transmits that data to the armed flying machines. In the time it takes the weaponized robots to get to that location, they've lost Reese. We could have all been spared another 90 minutes of that movie if the first drone had a machine gun, or a small pistol, or even just a sharp bit off to one side with maybe a little rust on it (if that's not, you know, overkill).