I say these things in regards to the OFFICIAL Forums.... (when they are opened, not this, the temp official forum)
Official Forums should be fully opened to the people that have bought ESO and have a current subscription open.
The ability to read the posts should be open to the general public.
If you have bought the game but do not have your sub active, you should not have access to post comments.
If you want to post comments, but have not bought and subscribed to ESO, you should not have the same access as someone who has; there are a number of other forums available on the web to do that.