I look forward to snowscapes with many tracks to follow. Perhaps easier movement through snowdrifts when following someone else's tracks...?
As things are, if footprints are an on/off feature easily added/taken away with a flag one/zero - then by all means remove them for the moment.
It could become useful data for some Zombie AI. If a players movements are translated into tracks on the ground, these tracks could serve as a location/direction and date/time stamp. Zombies could potentially 'catch on' to old tracks, follow fresh ones and generally deviate towards recent centres of activity.
The same data could be incorporated into a 'tracking skill' whereby recent tracks are able to be inspected giving rise to some player info? Metadata or whatever else is held. State of health? Heavily laden?