Why does diff not default to the unified format?

[Shriramana Sharma]

Hello all.

As far as I can see, the unified format is the most used diff format in 
the developer world. For example, patches are mostly distibuted as 
unified-diffs, debianization diffs are unified diffs, and so on. The 
unified format also allows fuzzy patching.

This being so, I would like to know why diff does not default to the 
unified format for its output? I would like diff to output unified 
format by default.

If there is a reason unified diff should not be the default, please tell 
me what it is. Else please make it the default for the next version of 
diff released.

Thank you.

Shriramana Sharma.