There are 3.5 million cannabis smokers in Germany. 84% of all Germans are pro legalization. So I think there is much room to grow for your forum. The current user base and its potential user base is off by orders of magnitude. It is not enough to work towards this goal by making small improvements or modifications.
Changes that placate the current user base might even inhibit its growth.
Changes are always tradeoffs. Something that might make life more convenient for a power user will put off a new user. At some point the barrier is so high, that new registrations dry up and the forum slowly decays.