I tend to agree. Leaves are thin so why light the edge? Makes little sense.
It makes sense in bloom. The buds develop tons of leaves that can accept light from the sides or even bottom of the plant. I've experimented with reflective walls, sun tan style reflection (like putting one of those funny metal things at an angle on your neck) and hanging LED fixtures sideways.
In my experience "side lighting" is going to fill in the lower buds a lot better, the same result can be achieved with proper reflectivity in the grow space, especially with HPS, CMH etc.. LED does tend to shoot more of a square direct downward light but that doesn't mean the light that bounces off the wall/floor isn't useful.
Again though, I would focus on a better primary light above the plant and if you have problems with light penetration maybe look into strategic defoliation to get more light down into the canopy and on the lower buds.