That's the beauty of a game that doesn't tell you how to play it and gives you several methods to accomplish leveling. There isn't one "right" way.
I guess if you wanna sit there and shoot into a cave and call that "fun," go for it. I just don't want to hear that you don't like the game because you aren't getting good loot dropping from it.
I also just have a hard time with people spending $60 to do that. I mean, really? I am not going to tell anyone how to spend their money, but, well, I don't think I should or need to comment any further on that.