I still think EXTERNAL should be specified when we create the new table.
"External" is just like the location where we store the table - we create a new table "like" the old table in every aspect except where the data is stored. Both "location" and "external" are descriptions of where the data is stored, so I don't think they should be inherited.
Also, there is no "internal" keyword, which means there is no way to create an internal table like an external table, if the proposed way is implemented. (I don't think there is a way to alter a table to internal or external as well)