Use Edit - Schema to create a new field of the desired type, and then the Transform pane, Copy template to copy from the old field/type to the new field/type.
8 is a bit casual about changing data types, which drives DBMS people nuts, because it is a risk of breaking many things by just right clicking a column head and changing the type. For example, there may be many dependencies on the field being a particular data type.
9 was designed for use with DBMS connections of virtually any size, and in that world people want more rigorous control. So 9 takes the more rigorous route: create a new field of the type you want, and populate it with data. That also gives you the opportunity for richer, explicit control over the type conversion process.
I personally think both approaches have their moments. If I'm just goofing around with a project for my own use where I know nothing sophisticated depends on the data type, sure, it would be nice to have the process of a schema addition, copy, old field deleted and new field renamed, to be automated in the form of a right click on the column header and then picking change type. But I also get it why more sophisticated uses want it the way it is now.