I miss a lot of my favourite smaller subreddits too. There's way more now popping up then there was a few weeks ago so it is getting better. It'll take time for communities to grow, we can't expect it to be instantly like our fave subreddits were right off the bat. We have to remember that our niche subreddits started small as well at one point. Also consider doing some posting in those slow communities yourself to get the ball rolling. I've noticed it takes someone else commenting and providing content before other people feel brave enough to join in too. Kind of like no one wanting to be the first or only person on the dance floor. Once a couple people get in there and begin dancing others join too.