I should also point out that current database implementations require databases to be in a consistent state within a transaction but can be in an inconsistent state within a transaction. Date's theory require that every atomic operation require the database to be in a consistent state at the end of the operation. By creating syntax which would allow this, many transactions would probably be unecessary, thus freeing us from yet another low-leve detail we shouldn't be worrying about.

Of course, you have tons of practical experience here, so feel free to ignore me :)

By the way, if you're going to be at the next PDX.pm meeting, I wouldn't mind getting together to chat about this.