Abt the slow growth… I would like to offer a little harsh criticism… The game, as a survival game, has a beginning game, and a middle game, but no end game.
Once you have become established, it can be quite boring. Once you have explored all the biomes, you don’t really feel like doing anything else. Now, that is the way I feel… noodles is a different type of player, he is content to slowly work away at a large project in-game… he uses mesecraft as a relaxation. However, for players that are there for interesting and stimulating experiences, you run out of things to do once you have played for a few months.
As an extreme example, I told BannanaNutBread about sara’s. He joined, played, a few weeks later had completely explored the game… (reached the primordeal layer) built some things, and got bored, and left.
To keep players, you will have to think about engaging players that are well established.