Why do you use parenthesis for ON clause? It is useless. SQL is not C or JAVA.
At this point in my career it's just a personal habit. I never programmed C, done most of my development in Java so maybe that's a subconscious influence?
I suspect it is partly because I seldom need to use "ON" but instead join with "USING" which does require the parentheses, so when I need to use ON I just keep them.
I agree they are unnecessary in the example and should be removed to be consistent.
