I think the software is just inconsistent.
I believe one of the items on the EA 'To Do' list is update the forum software ... someday. But until there's a single person (presumably running a team) driven and dedicated to doing so, it is unlikely to rise to the top of the priority list any time soon.
This is what happens in an organization run mainly by (passionate) volunteers. There's always more to do than people to do it, so the things that have to get done do (usually), and the nice-to-haves may get done eventually.