When you are building a game never been done before no matter how much experience you have its impossible to know how long or how much it will take. CiG have been doing the impossible for years, to build a company up from nothing while still developing a game at the same time is difficult for doing even a normal game.
The most important thing about a game is its final product, if you think otherwise then you are just lying to yourself, if a game is good it doesnt matter if it cost 1 billion to develop or took 20 years to make, the whole point in a game is that you want to play it and the game itself interests what you enjoy.
Building an MMO means the company will always be developing the game regardless of when it releases in a suitable version where it has most of what it needs.