See attached screenshot, every value and every closing bracket is followed by a comma. I suppose this might still be valid JSON/whatever format that is, but it'd be prettier and shorter without those extra commas.
MC-69320
Data tag output by /entitydata and /blockdata contains too many commas
Resolved
Fixed
0
Unconfirmed
Minecraft 1.8-pre1, Minecraft 1.8
Minecraft 15w31a
Retrieved
It's not about being pretty, and this isn't a bug. What would be the point if it looked nice but was inconvenient to use? It needs a parsing tag, and that's what the comma is for.