The Star Wars franchise is all about placing fantastical elements within in a sci-fi setting. In order to truly enjoy the films, you have to suspend your disbelief a little bit — otherwise it'll look a lot like cosmic samurai fighting a faceless evil empire across a galaxy filled with people who magically speak the same language and function just fine without a space suit wherever they end up. Putting a bit more thought into it, the Imperial Stormtroopers seem to get the short end of the stick nearly every single time. It is fun to remember why they probably wouldn't make the most intimidating enemy — especially not with the highly-overused AT-AT walker.
To all seven of you out there who haven't seen Star Wars, the AT-AT walker is a gigantic, robotic troop transport used by the antagonists that's sort-of a futuristic callback to Hannibal's elephants. They're fairly intimidating in the films until you realize just how dumb of a design they really are.
Its weaknesses are extremely obvious
The most glaring mistake of the AT-AT is that they're so easy to destroy. In The Empire Strikes Back, our heroes turn the tide during a battle on the icy planet of Hoth when they decide to trip the lumbering armor. Really? Why did it take some rural moisture farmer to make that mental breakthrough?
Not only that, but Luke Skywalker also destroyed one by throwing a single grenade, which, somehow, blows up the head. They're even more easily destroyed in Rogue One, when a single rocket to the walker's "neck" is enough to take it down.
Its only weapons are front-facing
If you're facing the front of an AT-AT, you're probably screwed. If you're literally anywhere outside of its 30-degree field of facing, you're completely safe.
Without any kind of air support, like what happened to them in The Empire Strikes Back, the opportunity to flank them is wide open. If you're thinking that it could just turn around, that brings us to our next point.
It can barely turn
To be fair, the AT-AT can turn a little bit in Episode V and some of the obscure novels (which are no longer canon) say that they have an additional joint under the plating to help it turn. But, even if we're generous, they can turn maybe fifteen degrees with each slow, lumbering step.
This is happens in a time when, according to the logic that has been established by the franchise, intergalactic travel and troop transport is done with spaceships. But, instead of carrying troops via something that fly, they chose something that can barely change course.
It wouldn't be able to maneuver anywhere
Let's bring things back to the real world for a moment and discuss why tank treads work in almost every environment while horses don't: Legs get caught in things. They get tangled in snares and sink into sand, snow, and mud. Tank treads, conversely, just roll through it all.
Now magnify that four-legged beast to the size of an AT-AT. All of those same problems still exist, but now you can cross cities and forests off that list, too.
It's a terrible design for a troop transport
Let's bring it back to the fact that they rely on what are essentially robot camels when they have countless other options at their disposal. A spaceship can warp in and push out every Stormtrooper in a blink of an eye. The AT-AT, on the other hand, needs to bend down, load troops into the vehicle, carry them all somewhere, bend back down, and, finally, unload them.
All of that just to get some troops forward in an easily destructible, undefended deathtrap that can barely get around. Sure, they're intimidating, but don't you have Death Stars and Star Destroyers for that?