Of course, we can view the car as a single purpose ‘move from A to B’ device, but there’s other viewpoints where the car has a performance (speed, efficiency, handling assist, smoother engine management) profile, quality of life and security features (auto cruising, speed limit detection, tire pressure detection, auto braking etc)
All of these should have evolved enough in 10 years that you get significant benefits from an upgrade.
Obviously new cars are in general an upgrade. Most people driving old cars do not do so because they want to, they do it because new cars are too expensive.
There's certainly degradation that occurs to a car with lots of mileage, but it's generally with the interior and the electrical systems. There may be some exterior corrosion, too, if you live in the appropriate climate though corrosion resistance has improved a lot on cars lately. And, of course, all bets are off if you don't properly maintain the car.
I should get around to replacing some suspension components to make it more comfortable to drive, probably will later this year when I get some time. They're not terribly expensive.
The other side of it too is accidents are likely to always be an issue with cars (even in a world of self-driving cars, I suspect), and there are plenty of other safety reasons cars shouldn't be expected to be driven for too many years without replacement.
Electric or ICE, as you hit 150-200k, you'll have long since worn through all kinds of rubber bushings on virtually every part, you'll be approaching the point where you've had to replace starter or alternator, you'll have (hopefully) replaced your suspension a couple of times, and so on. As the value continues to decline, the 'value' of spending parts+labor money on any of these replacements starts to decline.
It helped that I was able to get a brand new loaded Volt for $9,000 off plus an additional $7500 tax rebate. which in the end means that I have the best of both worlds for $25,000 with a full warranty etc..
Having said that, I remember that 20 years ago, those kinds of parts would need to be replaced after maybe 60-80k miles. However, everything seems to be better built now - my van has 214k on it, and no sign of needing replacements - same goes for all the cars I've bought and sold (20 or so) in the last 3 years.
Further on down the mileage line, virtually everything is wearing out. Rubber bushings in control arms. Rubber bushings in all your rear suspension points. There's rubber EVERYWHERE on cars, and it all wears out. Motor mounts, transmission mounts, shock mounts. Again, it'll still go down the road, but it won't drive like new. You might have a lot of slop in steering, slop in cornering. The car might pull one way or another under acceleration. It'll be louder, harsher, clunkier.
Going a little deeper, probably your tie rods and sway bar links are shot, as are the control arm bushings (which may or may not be integral with the entire control arm).
Not necessarily by design, it's simply inherent to electric drive, you have much less "metal grinding against lubricated metal with a controlled wear rate" situations that seems to doom ICEs and the associated transmissions on the long run.
Cars overall depreciate on the scale of 10/15 years or so. Right now the depreciation rates are the same. It's an interesting artifact of ICE vehicles that people don't expect any car's drive train to last more than ~15 years. It shouldn't be a surprise that car manufacturers were skeptical of battery tech right up until they hit about that same magic lifetime number. It also shouldn't be a surprise that car manufacturers won't have a lot of incentive to push it past that magic lifetime number, because that would affect car replacement rates and that would affect the bottom line.
Mostly battery replacements look to keep the used car / secondary markets busy, and if we expect to see interesting innovations in battery replacements that's probably where we'll see them as more electric cars get resold to secondary and tertiary owners. (Just as we see the used car markets pushing innovations in after-market parts in general.)
You are right in that maybe leaves room for a disruption that someone might be interested in a "car for life" model where electric cars might be built far more sustainably with an ideal towards larger reuse of the vehicle over the owner's lifetime and a larger depreciation scale on the order of multiple decades.
That would be a huge game changer, and would potentially be great for the planet (less steel production alone, conceivably). It would also take a lot of work to make it happen, given the existing industry reliance on the current business model for most of a century now. It would also be one extremely huge disruption in so many downstream industries, secondary markets, etc, to the point where it may be more of a revolution (in the industrial sense, but also perhaps the war sense) than a "simple" disruption.