I think it does exist for fun or lose. (after playing 15 hours with only heavy body type without a rest, I realized it is just uesless.)
delete the heavy body type or increase the health point of heavy body type or something. I am a very experienced gamer not a stupid [censored]. but I lost every game and couldn't kill many enemies with heavy body type for 15 hours. it proves it is useless.
If you can't win with the heavy then don't be a heavy. Everybody seems to think that because they can't do something it must not work, but that speaks more to your playing style than the game.
The health points make a little difference, but the big difference is weaponry, whether it be the heavy weapons (all of which are useful) or using two medium weapons which also works very well. If it's not for you then it's not for you, but he works great, just differently, from the other types.