Ask the publishers about this. The publisher set a date when the game is suppose to be finished. Most games are not finished and are rushed at a curtain part in the development. Developers are not going to catch all the bugs. Eventually you have to make a tough decision to release the game in 'as is' or delay and potentionaly lose millions or not ship the game at all.
Why put all your ideas into one game? Why not save some for 'number 2' or expansions/DLC? DLC/Expansions are suppose to lenghten the games time, but a lot of companies abuse this by giving bulls#$t products. Those companies know they have a cult following them so they'll make money.
What millions of gamers don't realize is theres a lot more going on behind the scenes then they think. Any thing can happen which slows the dev process down or stops the game from ever seeing the light of day.
"90% of what is considered "impossible" is, in fact, possible. The other 10% will become possible with the passage of time & technology." -Hideo Kojima