Quote from The Vault Dweller
He has confirmed that there is still a lot of stuff he has added that hasn't been leaked yet, so outlooks are good.
Comparing Mojang's 9 months to the modder's 4 is unrealistic due to the amount of time they actually spent working on improving the game and not doing special events like E3 or award giving stuff. If you wanted to accurately comparing it, you would get all the hours they spent working on the game then multiply Mojang's hours by 1.5 as they have one less coder than the modders who worked on the Aether. That would make it a fair fight and show who has the better skills. Just because one team has more players, it doesn't mean the overall team quality is good, just that more can be done with more people.
Aether was released with more bugs in it than a bee hive, at least mojang tries to make sure everything works right.