Are you seriously trying to say that if you're talking about a solar panel it makes more sense to talk about how much energy it produces per second than per hour. If you wanted to think about the amount a panel can produce per day are you sitting there thinking about how many seconds of sunlight it will get in a day.

If you want to estimate the energy usage of a 400 watt lighting system during an 8 hour workday you think it's more intuitive to go 400 * 3600 * 8 / 1,000,000 than 400 / 1000 * 8?

The reason seemingly every electrical utility in the world uses kWh is because hours are the more intuitive unit of time for this context.