It's not about genre, it's that tanks from the 1940s on seem far more suited to battle than what should be much more advanced technology
I still don't think I agree with the comparison, if you are purely comparing them based on how well they suit their purpose. In 'Empire,' those AT-AT walkers were mowing down all of their ground forces, their shield generators, and their entire base. They're essentially invincible, giant walking tanks, their only weakness lying in their lanky legs. An excerpt from Wookieepedia:
"The AT-AT's formidable offensive capabilities were supplied by dual, chin-mounted Taim & Bak MS-1 fire-linked heavy laser cannons for slower, more cumbersome targets and two fire-linked medium repeating blasters mounted on each side of the head designed for lighter, agile targets.[1][3] The two sets of weapons could be independently rotated in order to engage multiple targets at once.[3] However, the AT-AT head, which could move between a range of left, center, and right firing arcs, could only rotate one fire arc per heavy laser volley.[2] The walker's strong external 9095-T8511 grade durasteel armor was virtually impervious to all but the heaviest of artillery weapons."
Plus, the Empire could basically drop them anywhere they wanted in a moments notice, and because they were tall and thin, they could traverse more terrain.
Here comes my inner history buff now:
I think it's very difficult to say that a tank in WWII would be more suited for its operation than an AT AT in Star Wars, at least, not to the point that you are arguing. One important thing to keep in mind is that technology in WWII surpassed the technology of the previous war, especially in regard to heavy artillery and anti-tank defenses. (Explosive anti-tank ammo, the Panzerfaust, Jagdbombers, etc.) This presented a dilemma in certain circumstances. (Off the top of my head, when Hitler decided to joyride southward, he ran into the Maginot Line, which had an incredibly complex anti-tank setup spanning the French/German border. These kinds of setups became common in many of the warring countries because each country was beginning to develop tanks at an ever increasing rate. (Though Germany's Blitzkrieg tanks were superior in many ways, surpassing British engineering that once dominated WWI.)
Now, that's a catch twenty two when arguing the validity of tanks in the war, because even though there were advancements to defend against them, they were also much more powerful. The French failed in the sense that they didn't expect the Ardennes to be penetrable by tank. (Huge forests near the Belgium-facing side of France) But... they were penetrated by tanks and the Germans took a joyride through neutral territory in Belgium to essentially circumvent the entire wall and its defenses.
Now, as you can see via the quote from Wookieepedia - there weren't any anti-AT-AT developments, or at least, developments in artillary the rebels had at their disposal - I doubt the rebels were even familiar with them before Hoth. If Luke hadn't decided to start going for their legs, the rebel base would have been lost much quicker. (Though it is important to remember that in this battle, the Empire DID win, and they DID destroy the base, using AT-AT's - so clearly they were effective.)
So, I wouldn't compare them to the tanks of WWII and say that they're inferior in design. They had one weakness that was still difficult to exploit, and certainly not quick enough to exploit where the rebels could destroy enough of the AT-AT's to not let them destroy the generators. (Well, two weaknesses if you count a bunch of Carebears ramming their sides in with giant logs...) The tanks of WWII had plenty of weaknesses - weaknesses that each party exploited upon one another during the war. That said, I'd say they were equally maneuverable, though, which is why I mentioned the Ardennes - because the Ardennes wouldn't be much different than the forest on Endor.
So, to conclude my random history post - The AT-AT's were suited for their purpose equally, if not more so, than a tank in WWII. To conclude that the tanks of WWII were far more apt at their duties, I think, would be incorrect.
Woohoo! History and Star Wars! That's the most fun I've had as a nerd in a long time
