Wheels can get stuck and destroyed

And you think legs, wings, rotors, or tentacles can't? More importantly, you think any of those are more durable or dependable than a wheel, the simplest of all machines (Save for maybe a ramp?).

and wings require the robot to keep moving

Depends on what exactly you're saying there, but I think I catch your drift, and is absolutely a valid point, except, drones can land. Many of the designs in use today are VTOL as well, so, as cats, say, if it fits, it sits, no runway necessary. Also, using ultralight and glider concepts, solar, and lighter-than air tech (balloons/blimps), it's possible and fairly simple to keep drones aloft indefinitely, even without moving parts. All of these are tried true designs that are simpler than bipedal kinematics, or any sort of tentacles.

Tank treads are the simplest ... choice for an autonomous war robot,

We mostly agree on this point. Simple wheeled platform is technically simpler, but I think we've pretty well proven in multiple wars and scenarios that treads absolutely have a place in mechanized warfare. They do have some drawbacks, and wheels and tires are still nearly ubiquitous for several reasons, but either way, both are effective and comparatively simple forms of locomotion compared to the others in discussion here.

but in a perfect world the robots would look more like metal octopuses

I think you've watched the matrix or Edge of Tomorrow a few too many times. Unless by "perfect" you mean a scifi scenario where several significant breakthroughs in elastic electroactive polymers (or some sort of analogous (bio)tech) make them in anyway reliable, much less easy to manufacture, maintain, or repair. I admit, that'd be fucking cool, and would love to see companies pour money into this, so many amazing uses for such a thing, but with our current science and tech today, that's a pipe dream. EAP/EPM's just aren't very reliable. Some show pretty impressive qualities and strengths, and obviously they have potential, but most all of them have significant drawbacks: currently most notable is that they're pretty fragile. It's also exceptionally easy to disrupt their function with outside electric stimuli. Now, all electronics are technically vulnerable to such things to a degree, but at least when your cars battery dies/electronics are fried/has its engine completely removed, you can still push or pull/tow the thing and it will roll. Even with a flat tire it will be easier to get moving than some form of appendaged kinematics platform that has been disabled. Now I'm getting off in the weeds here, and while I concede that would be amazing useful/super cool technology if we could perfect it, "octopi infantry" is still not going to be a better platform than your standard wheeled or flying infantry, at least not for scale. For specialized applications, yeah, most probably, send in the killer roboctopus, but for the "Grunt" of your autonomous army, you're looking at something on wheels or wings.

The simple truth is - boring as it may be - is that when you consider maintenance, manufacturing, logistics, and economics, the simpler almost always wins. It's like the old addage of escalators: when it fails, you still have stairs. When a wheeled platform fails, you can usually still pull/tow it - and thus move it. So while multipedal systems are capable of tackling more complex terrain (eg, stairs) they simply aren't as capable as handling a flat and level floor as well as wheels or tracks. Furthermore, flying drones are cheap and easy to build as well, so while robocop can climb stairs or rubble, robocopter can just fly straight to the rough, even if the stairwell has collapsed. So when it's easier to fly (and build machins that can fly), why walk?