I think people mainly use it to see where people stand with reputation, and post count. I've also used it when searching for certain useres that I remember, but can't quite remember their exact username. A search by location could be useful for finding members who live close to you. Or, maybe a way to sort the members based on their distance from your specific location. I also think that only active and contributing members should be included in the members list. This would cut down the size by a ton!