[nkuttler]

> It lets you comment out a line without having to remove the trailing comma from the previous line

That would only be an advantage above comma at the end on the last line. It really only moves the problem from the last line to the first one. Now you can't comment out the first line without removing a comma...

[diroussel]

In the comma-first method, adding a new element at the end produces a one mine diff. But when doing comma-last method, then adding a new element to the list gives a two line diff.

It can make resolving merges just a little bit easier.