Well no, not really, that was just a personal preference on my part. Your problem is that you were trying to make the output 2 fields instead of 1 (called [Structured or Unstructured] and Annuity). For your purposes this doesn't work.
You were trying to create a field called [Structured or Unstructured]. Then, in you IF statement, you were using the word "Unstructured" (having absolutely nothing to do with the field you created). It doesn't work that way. You can apply a map conditionally, it just has to be done within 1 declaration. Or with a preceding load. For example:
LOAD if(myfield3='ABC','ABC',myfield2) as finaloutput LOAD applymap('mymap',myfield1) as myfield2 ;