I agree that typing is a good thing for some applications, however I think the arguments against requiring typing in Perl could be made for a database. Yes, having constraints on the data that goes into the database is good for efficiency, reliability and performance - hometimes I'd like to optimize for development time.

For example, a small unimportant system that isnt going to hold much data, or a prototype that needs to be rapidly developed with a small investment in developer time.

A typeless relational database has (would have) applications.

And as for never having to use type conversions, what about shortening a string, or converting a numeric string to an int. Or making sure that the number is low enough to fit in a byte. etc etc.