I actually quite like the system the way it is... mainly because of all the " Cookie Monsters " who turn up in the game ... and I think most of the people on here have met those in their Achat play.
Free users are able to read Forum but to be allowed to post & vote , I do think that they need to show more commitment to the game either by paying for a subscription or a least having the conversational skills to be offered a gift and use that gift to register here.
It also helps to filter or at least limit access to under age people & for Forum to be abused by anonymous people & multi accounts. Voting for example could be seriously disrupted.
I do see your point that we may lose some good ideas by not allowing initial free users Forum access but the cons far out weigh the pros.
Free users who are committed to the game, can always approach a member if they so desire to discuss any ideas they may have or , such as the Secret Game dates asked to be included. The premium member can then post the idea on their behalf or ask to be included in the game as long as the Director of the game agrees.