Part of it was the suspension system on the a Panther and Tigers. The interleaved road wheels gave a really smooth ride, but at the cost of difficult track maintenance. Repairs to an inner road wheel requiring the removal of three wheels (2outer and the inner) to accomplish.
The wheels are not really part of the suspension, and it really was the suspension torsion bars that gave the smooth ride, rather than the number of wheels, but I think I can understand what you're trying to say.
The thing is, if you look at it, it's far from being over-engineered, since it's something that was rushed into production because heads would roll if someone reported a delay. It's not like someone sat and thought how to make it more sophisticated. They just took the design for a test vehicle that wasn't even supposed to be the final version, and just fit more wheels until they could take the weight.
The biggest restriction there being that the wheels actually had rubber tyres, which would get squashed and destroyed if they had to take more than a certain amount of force. So essentially you had the weight of the tank, divided by how much weight could such a tyre take, that gave you the number of wheels. And once you have that number, it starts to dawn that either you make a 100 ft long tank to keep them in a line, or you use more than one row of them. It's really that simple.
Later, when they could change the design, they replaced it with steel wheels, which got rid of two rows of wheels, leaving it overlapping instead of interleaved. They still couldn't completely redo the design, though, because changing the axles and suspension was essentially design and retooling that nobody wanted to pay for.
So essentially instead of being OVERengineered, it was something actually UNDERengineered.
Plus, there's the aspect that suspension and tracks were not actually designed for comfort (nobody really cared that much for the comfort of soldiers), but to (A) spread the weight enough to be usable on soft, muddy ground, which was actually the biggest problem in Russia (though it then proved to not be a very good solution, when that mud could freeze between your wheels), and (B) so you don't have mobility problems on rough and uneven terrain.
And then there were the engines, the Germans chose to go with gas, a reasonable choice in the West where they could even use civilian filling stations in a pinch, but gasoline is very volatile which means it's easier to set the vehicle on fire. Also, the engines were manufactured to the usual high standards of German auto engineering, and we're simply incapable of being manufactured quickly.
You do realize that the USA used gasoline engines too, right? There's a reason why the Sherman was called the "tommy cooker".
The more mundane explanation is that there was no such choice available at all. Germany just didn't have a Diesel engine designed, that could move such a massive tank, and again it had to be ready by a very tight deadline
or else. The "choice" to use a gas engine had nothing to do with using civilian gas pumps, and was simply a matter of that being the only engine they had available "off the shelf", so to speak.
Basically the choice was either use the available Maybach engine, or explain to Hitler that you blew his deadline because you wanted to engineer your own better one. Which choice would YOU go for?
Again, it hardly was OVERengineering on the part of the designers of the Tiger. More like UNDERengineering again, as all they had time and funds to do was figure out how to use a given third-party engine.
