I needed it recently--I was driving around downtown LA while talking to a friend and trying to use Google Maps (he was trying to guide me somewhere and I was having trouble finding it). In that case I happened to have spotty coverage and my phone switched to edge and so I couldn't do it and that was adding to my frustration.

Also talking on the phone and needing to look up a reference happens surprisingly often. It's really nice to have data available while talking.