Apparently that's a limitation of the forum software itself. It can't make distinctions like what reward tier you've got filled or whatever; it can only look at your account and say, "yes, VIP," or "no, not VIP."
FUN FACT: That burst of light when you level up is actually the effectiveness escaping from your enhancements all at once.
I think there may be a couple of issues at work here as to why there is no distinction between Free and Premium and why there aren't separate levels of access on the forums.
One is that a decision was made to tie the forum login to the game account when they switched to vBulletin. The NCSoft billing system only differentiates betwen two types of accounts: Free or Paid. There don't have a way set up in the billing system to differentiate between completely Free and Premium accounts. Since that is the system tied to for forum authentication, they would have to rewrite the code for the system to make that distinction.
Second is the Seattle web team. They are the ones that have control of the forum software. I'm not sure I'd trust them to handle setting up a third type of authenticated access for Premiums.
If the game spit out 20 dollar bills people would complain that they weren't sequentially numbered. If they were sequentially numbered people would complain that they weren't random enough.
Black Pebble is my new hero.
Currently, there's no distinction between Free and Premium players on the forums. I'd personally like to see more of a distinction being made between the two groups: I'd personally be happy with allowing Premium members to (at the very least) participate in the server boards in addition to the All Access sections, but no more than that.
At the same time, I've done research into another MMO that does let former subscribers keep all of their forum access privileges even if they happen to lapse.
Whether or not this happens is hardly a dealbreaker for me considering I have other avenues open for at least connecting with supergroup friends, but it could be a huge boon for Premiums who regularly interact in their server communities and would rather continue to do so than be mixed in with the general All Access crowd.