On our longer trips my wife is always complaining about our bikes, generator, etc getting wet so I went out yesterday and bought a truck camper top. I now feel old.
As you get older you get more practical. Yes, it's practical to put a shell on your truck.
With all of the rain we get here in the northwest and having a smaller trailer it made sense for us to put a shell on our truck to keep everything dry and it is comforting to be able to lock the shell, leaving bikes and such in the bed of the truck, when I run into a store or similar.