Why So Big?

I was walking to the gym the other day and I passed a BIG truck that was parked along the way.  Now, I was on the sidewalk (duh) which is... I don't know how "tall" actually, and then I had on my runners, so another inch or so and the TIRE of this damn truck came up to practically my shoulder.  If I had been on the street, I think the tire might have been as tall as me?  

I looked, it was a (Dodge?) Ram 3500, so not like a business truck, just a GIANT truck you or I could buy off of the lot and drive.

I have no idea why it needs to be that big (sure I get that some folks pull fifth wheels or big boats and stuff, but this didn't seem to be a towing type truck).

I have no idea why a truck that isn't a commercial vehicle needs to be big enough that the driver wouldn't even be able to see most, if not all of me, out of their front window.  It's crazy.

I know I'm not the only one that feels this way but man that was insane to see it THAT BIG from the sidewalk, you know?