Resident Merchant?

I purchased Resident Evil 4 a little more than a week ago and I have to saw that I'm enjoying quite well despite severly disliking the previous installments. I just hated having to shoot in the older games because of the very poor aiming system in which you swiveled on your heels and hoped to be aiming in the right direction. What surprised me with RE4 was the fact that it's not all that scary. Compared to Doom 3, RE 4 is rather tame. However, I've found myself panicing during the game due to the fact that it can be rather difficult to stay alive. There were times where I was holed up within a derelict house shooting zombie-like villagers (called ganados) coming in through the windows when suddenly the feared chainsaw-toting guy with a burlap sack somehow sneaks behind me and one-hit-kills me by lopping off my head. However, this has proved to be quite fun and worth the $50 (I rarely buy games at full price) I paid, further justifying my purchase of the Game Cube system.

Now what bothers me is this. All along the way through the game you encounter the "merchant." He just happens to be one of the few non-zombies throughout the games and sells you weapons as well as upgrades them. Sure, this is nice, but still, why the hell is he there? It just doesn't make any sense. You can kill him though...

"...DRAIN YOU OF YOUR SANITY
FACE THE THING THAT SHOULD NOT BE..."

Song of the Moment: "The Thing That Should Not Be" by Metallica