For me it's not about being the same character (like you've mentioned, opening and closing braces aren't either), it's about commas and braces indicating different things in the hierarchy. Not to mention the symmetry breaking: an opening brace together with data in a line, then a lonely one at the bottom.
In a series of declarations, the lonely closing brace at the bottom can be treated as a substitute for an empty line between two entries, as it produces a similar sparse spacing.
