I feel like the reason StarVault is always so persistent in releasing their efforts is because there's a money problem. They need to be able to fund the development of the game and the only way to do that is by having an active player base that subscribes. Perhaps, in their eyes MO2 is so beautiful and well put together regardless of what it is currently lacking, and it proposes such an interestingly intricate gameplay that no player would not want to wait for the full release of the game.
However, this ideal is still flawed, even if it might work.
There will be different niches of players... people will want to explore the dungeons and see the bosses with guild guides where the new players could just absorb the extraordinary experience of a MO type dungeon, which is majorly different than any other games dungeon.. But people who like butchering and getting crafting things that you get from the wildlife of the game.
If they release the game too soon, there will be lots of new players who might not want to wait for the final release. MO1 has remained generally small because it lacked a full release where anyone could just join and experience a fully built world with many features. etc..