Are you seriously saying that when you're talking about a solar panel you care about how much energy it produces per hour, not per second, per day, per week, or per year?

If you want to estimate the energy usage of a 400 watt lighting system during an 8 hour workday

Why would you want to do that? And what kind of lighting system in 2026 uses 400 Watts?

Are you seriously saying that when you're using your 2000 watt hair dryer, you want to pretend that you used it for an hour, and then scale that back to the few seconds you actually used it? Are you seriously pretending that your 800 watt microwave oven is on for a full hour at full power while you're heating your nuggets, so it makes sense to think of it in terms of kilowatt hours?

The reason most people think kWh is intuitive is that they're used to it because their electrical utility uses it. It's the same reason that Americans think Fahrenheit is more intuitive, while the rest of the world thinks Celsius is more intuitive. It's why Americans think miles make more sense for measuring distance, while the rest of the world thinks kilometers are easier to use.