Sure, I try to write short scripts and split them into separate scripts if they become too long. But nevertheless, sometimes I loose track of where an if structure starts (not so difficult to find) and where it ends!
Especially when the if structure contains also other if structures and it becomes a long construction.
Then being able to collapse some of the if structures you are not working on (or to view the structure of a script) would be very useful (in my opinion).
Perhaps it would even be useful for loop and other statements.