[dubya]

The simple text format also makes it somewhat scriptable, so you could make more complex figures than you could make with a mouse, without learning Postscript.

[SemanticStrengh]

What are fig advantages over SVG though?

[dubya]

SVG wasn't an option at the time. Now, support for TeX labels might still be an advantage. These days I just use PGF/TikZ.