OK, this is sort of a more personal entry where I blabber without reaching any kind of conclusion.
When you work for some company, your primary concern probably becomes money. Of course, you might like the people, the work you do, the game you are making. But you need money, and you are working on that game for money. If you aren’t making that game, you will be starving. On top of that, you have resource limitations, like time, money and people. Eventually, the game takes shape around those resource limitations; features added or cut, parts of story being cut, some parts of the game itself being cut, voice-overs being cut etc. Even with all the initial planning and designing, you witness a great deal of sacrifices for the game to be released, and, you guessed it right, to make it bring money.
When you go and think about creating a game, you try to define the experience and visualize things in your mind. There is a scenery which you try to achieve through the development process, a scenery in which you want to make the player… sense the experience you designed. You design all the components of the game pointing in this direction. There is a reason for each.. thing in the game to exist, a reason given by you. Everything that you put in the game together form that experience.
From what I understand, this first “Oh my! That’s totally gonna be so cool!” design, is somewhat personal. People usually fail to deliver this enthusiasm to people around them, so they get the game done by themselves. Or if they are not alone, they get to decide on important matters. The “other” team members are of course contributing to the project, but mostly by doing the tasks given to them.