The only danger I can think of is a developer using Capistrano to rollback a migration on the production database. Are there any other risks you can think of and what's the best way to avoid accidental migrations/database reset, etc?
edit: We do have daily backups in place. I would rephrase my question this way: Is there any benefit in not using migrations at all (manual schema changes only)? And do you know any Rails teams doing it?