Agreed! However, data cleaning is a pretty hard problem. My previous company stored merchant credit card transactions, and these transactions were large unwield

Agreed! However, data cleaning is a pretty hard problem. My previous company stored merchant credit card transactions, and these transactions were large unwieldy beasts whose data model had changed many times over the course of the company. Old data was completely invalid, and yet we couldn't remove it because the dollars and cents had to add up. The cleaning significantly hindered new development. Validations when storing new data definitely help, but changes to the data model are tough to reconcile with old data.