having a body truly does a lot to help protect the RC, I though similar to what you did, but they help to protect from rocks and debris from general running, helps keep the inside of the chassis cleaner, not as much dirt and grime build up around the internals, ESC fan, bearings, motor, spur gears, driveshafts, etc. sometimes might not seem like it does much to protect that stuff, but really does lol. also, it helps for crashes, the body absorbs a lot of impact when landing upsidedown so more or less acts like a cushion, it also disperses weight so when landing upside-down the shock tower/body mount assembly won't take the full force of the vehicle's weight and momentum.
have watched a few reviews from JayTee RC, I think he does well at reviewing the products, and not sales pitching, he also does a variety of name brand, cheap, and everywhere in between it seems.