Why Regenerate Snapshots For Merge Replication
The assumption I think with the default setting it that you'll be pushing out new subscriptions on a regular basis.  You don't need to do this, however when you push out a new subscription you'll need to manually run the snapshot agent (which really isn't that big a deal).

When the subscription is created the distributor will store information about the subscriber so that the distributor has this information available for cleanup and data distribution.