My guess is that it allows you to deliver the spell to multiple creatures using the spells new range. If the spell was touch before and the communal version says creatures touched, you can affect creatures at whatever range category reach spell gives.
Just looking at Communal Endure Elements as a template, it says "Target creatures touched." As such, you could use the Reach Spell metamagic to extend that to close, medium, or long range as described by the feat.