mobs who have their generic.follow_range attribute modified seem to have their random wandering behavior affected as well, even when not following anything.

For example, use

/summon pig ~ ~ ~ {Attributes:[{Name:"generic.follow_range",Base:0.0}]}

and compare its passive behavior to that of a normal pig. It will not move from its place at all.

The base value for the attribute seems to determine the maximum distance a mob can wander in a single movement. If this is intended behavior, the attribute should be renamed 'generic.pathing_range' or similar.