Verbal communication is far richer than written. You gain insight into how a developer feels about aspects of their work. Is there something they're not happy with but aren't comfortable talking about, are they enthusiastic about something which motivates other team members? Team dynamics can't be distilled into written communication. The standup can surface things like tensions between team members or a drop in morale. It's not just there as a status update, it's there to solve softer problems to help turn a group of developers into a great team.
