When she makes that position

They served different combat roles. The TE was made to be effective at fighting a cold, unfeeling host of metal enemies. It was for a time of war where uncountable identical men fought uncountable identical machines. The AT-AT was made for a time of subjegation, it wasnt built to be amazingly effective at as a main battle vehicle. It's an armored troop transport thats designed to be imposing. It's massively tall for intimidation factor, and all of its weapons are entirely front facing because its meant to be used in lines, slowly advancing on an enemy thats weapons cannot penetrate the hull of it. It existed to terrify the subjegated and move soldiers around.