With all this discussion of beam pattern and cutoff, let me illustrate what I'm talking about.
First photo is from my 4Runner with the halogen bulbs. You can see the hotspot of the beam, the cutoff, and some light bleeding up above the cutoff:
This amount of light bleeding up above the cutoff is not too bad, because the overall brightness level is low.
But look at what happens when you put very bright LED's in place of the halogens (photo courtesy of OP on this thread):
The amount of light in the hotspot is insane, but so is the amount of light bleeding up above the cutoff. See how the whole wall is lit up? That's what the drivers in front of you see as well. Some may choose to ignore it, being content with how bright the lights are, but that's the part that's bothering me.
For comparison, as unfair as it is, here is a photo of the light pattern on my HID retrofit project in a Chrysler minivan:
The light is bright and uniform, with no light bleedthrough. If our trucks didn't look bugeyed with projectors (IMO), I'd be doing a retrofit right about now.