Sounds like you don't want one so you've answered your own question. As far as why people do, I would guess that population won't commute 300 miles on a regular basis. Unless I am travelling I rarely run my truck more than 15 miles in a day. 50 if I am really running around. Initially I was scratching my head about an EV truck. But I am sure I am like a lot of people in that I am within 20 miles of a HD or Lowes. I could use this truck to get building materials etc, groceries, to the beach ( I live near the beach), pretty much all my usual running around. Once the light bulb went off that very few people travel an EV's range on most if not every day of the year, it starts to make sense. Being an RV'er, we look at it through the lens of the long distance travel. But we are a minority. An EV truck would probably suffice for 90% of the people who own an F150 today.
As a footnote, the 300 mile range is optimum conditions. Weather, terrain, running the heat or AC etc will all impact MPW (miles per watts). I suspect real world conditions the range is less.
And as others have said, the overnight charge is a worse case scenario on a standard outlet. Chargers made for EV's would charge at a much faster rate.