[dragonwriter]

> It lets you comment out a line without having to remove the trailing comma from the previous line. That'd be useful if JSON had comments.

It also lets you remove the line (for the same reason that you can comment it out) without modifying other lines. This is somewhat convenient if the file is one that you are going to manually edit (and even more useful if it is going to be the subject of line-oriented diffing tools, since the only changed lines will be the ones with meaningful changes.)

I'd agree that its less readable, though.

[lucio]

it also let's you add a line at the end (most common case) without modifying the previous line.

[jkrems]

If you use alphabetically ordered keys (a pretty good practice anyhow), that advantage goes away. If you just develop a habit of adding stuff to the front where semantics do not matter, that advantage goes away.