Brush you cannot get through not important to crappie. It must be something bigger fish can not get through yet be close to foraging area.

What you describe is similar to strip mines for coal before reclamation was law of land. Such can be very tough to get through on boat and be scratchy when you swim it yet not provide usable cover for the smaller crappie.

I have spent time watching crappie schools stacked up around cover. They would drift a few feet from it and start engulfing water that critters small enough I could not see them from from 6' away. When a bass would come through the school would pull back into the cover although to my eye not an area that should stop a bass of the size appropriate to catch the crappie. Fliers do the same thing.

Aquaculture
Cooperative Research / Extension
Lincoln University of Missouri