Here's where you're wrong.

Except for the aerodynamics, the other problems are easily solvable by a little extra hardware and a little extra software.

but there's no reason to solve them. There are no vehicles that are ambidextrous. Not even Amazon's warehouse bots are ambidextrous. There's zero need here other than "it would be neat if."

You put four wheel disk brakes (which many performance cars already have), then let the computer decide which two get the most pressure.

Right. Sure. And they're the exact same size, right? The rear discs aren't any smaller than the front? And the venting is symmetrical, right? And the geometry of pad and spindle are symmetrical, right?

This is just physics: You put the front brakes in the back and you've doubled or tripled the weight of your back brakes for no reason other than "I don't believe in 'back.'" Never mind the fact that you now have to gusset against two different directions of stress, rather than one or the fact that the design of brake pads is asymmetrical to improve cooling, reduce ablation and minimize weight.

It also isn't up to the computer as to which gets more pressure - when you decelerate the center of gravity shifts forward. It just does. This is why you turn tighter if you accelerate into a corner; the CoG moves backward. So you can either design for efficiency or you can refuse to choose.

Then you put four wheel steering, with similar computations.

Except that the added complexity of steerable, driven wheels adds an easy 150% to the assembly weight of an unsteerable wheel. And you're never going to use it. It's possible to parallel park a 4-wheel-steered vehicle such that it can't be unparked - it was a going concern with Mules.

Sure it would add expense, but these things are already going to be phenomenally expensive for a while.

Disc brakes and CV joints aren't cutting edge by any stretch of the imagination. The expense isn't in the management which is also old hat. The expense is in the physical components.

You only really need a fast back when you're racing, and nobody is racing a self driving car for fun on the weekends

Also not true. Aerodynamics determine fuel efficiency and once you're in a turbulent regime (in air, anything over 7mph) you're there. The overwhelming majority of aerodynamic improvements instituted in the past 50 years are all about efficiency - that's why spoilers are generally articulated these days, so they don't cost you 10MPG when you don't need them to.

Gentle reminder: I have a degree in this shit and have built 4 electric cars. I don't do it anymore but I did the hell out of it for a while. Symmetrical cars buy you nothing and cost a whole lot from a physics standpoint, not an electronics standpoint.