The truth is that almost nobody actually needs a computer that can last more than a single eight-hour workday on a single charge. In fact, most people need even less than that; if you're working somewhere with wifi, you're working somewhere with electricity. It's rare that I need my laptop to last more than two hours, let alone eight.
I agree with most of what you said, but I think this isn't necessarily true. Many people who want to work from a cafe have access to wifi but not electricity. Sometimes those outlets are in high demand and most people don't get one.
Or maybe you're on a plane, and your laptop is trying to draw too much current than the plane's crappy socket will give you (this just happened to me on a flight a week ago), so it only intermittently charges, but not enough to keep the charge percentage from steadily dropping.
Not wifi, but you might be tethering to your phone, away from electricity entirely.
Or maybe you just are offline entirely, without wifi or electricity.
Granted, I do agree with your overall point: the vast majority of the time my laptop is plugged in, and when it isn't, I expect I'll be near an outlet again within 2-3 hours at the most. Though I wonder how much of that is inherent to my usage patterns, and how much of that is me modifying my behavior because my laptop gets pretty bad battery life.
Most people don't need laptops, or nice monitors, or ergonomic desks and chairs.
The issue with arguing about need in this way is deciding who is the arbiter of what people need versus letting them buy things that they find useful or convenient or just nice.