This change was made to fall in line with other .ini parsers, it is after all an "official" configuration file format: http://en.wikipedia.org/wiki/INI_file
Using # was an extension on top of what is allowed in Windows...
Per that page:
"Some software supports the use of the number sign (#) as an alternative to the semicolon for indicating comments."
What's the 'official' definition of the ini format and what's really not allowed?
Isn't it nearly universally accepted in every other language?
Let me know if you spot the developer discussion on this logic?
(update: apparently this started with 5.3 not 5.4)