It turns out that a car that is good for consumers is almost never good for GM. Who could blame GM for scrapping a $20K car with $4K margin or a $40K car with $5k margin when they can use their resources to build a $30K car with $12K margin or a $65K truck with $30K margin?
Innovation is cute and everything. But profit is king.
One thing everyone forgets about the Volt and the timing of it's demise; the end of production coincided with the phasing out of a lot of the tax credits/incentives provided by the govt. For most of it's life it was a 40k vehicle you could get for closer to 33k.
GM likely saw the writing on the wall, people probably weren't willing to pay the full MSRP. Especially when Kia/Hyundai is managing to provide plug-in hybrids for 30k. (As far as quality/fit, I sat in an early Niro Plugin and the interior was something in between the Bolt and a Sonata... but some people care more about price nowadays.)
Whenever I get frustrated with GM killing off another promising project, I try to be fair to them about what their motivations should be.
GM doesn't mind selling a $40k car instead of a $33k car. What matters is volume x margin. You hit on the volume factor. I suggest that GM could have increased their volume dramatically by actually marketing the car. In my opinion they actively discouraged sales. They did not want to sell more of them. I think this points to a margin problem. Every hour of labor and every square foot of production facility given to the Volt was actually hurting GM. Not because the Volt had a negative margin, but because the Volt had a negative _relative_ margin.
If GM layed off every line worker/engineer/artist etc working on the Volt and closed every production facility that manufactured it, GM would have lost money.
But if they repurpose all that into the production of a 1/2-ton truck, they make more money than they do on the Volt.
If they repurpose it all into the production of the Bolt that sells for $40k, they make more money than on the Volt. You can argue that the Volt is 2x or 3x better than the Bolt. But that would be arguing from the wrong perspective. With a little marketing the Bolt should sell as well as the Volt (even at a higher price tag) and provide significantly higher margins. Same volume x higher margin = kill the Volt.
Innovation is cute and everything. But profit is king.