When changing a data type from text area to long text that is also referenced in a class we were forced to backup the class, delete it, make the data type change and restore the class -- provided we're in development or test.  Unfortunately, in the production instance of salesforce,  we cannot delete a class. Instead  we'd have to move an empty version of that class into production to temporarily eliminate the dependency, update the field, and then push the correct code back in.  This is way too complex since we are talking about 12 different fields and 6 different classes / visual force pages. 

How can we simplify this and just make the change to the target fields?

And why this dependency anyway? Why is salesforce blocking our efforts in this way?