10 Hour Game

At our meeting the last week I had asked a question that only now I realized the repercussions. "Are we making a ten hour game?" After posing this question, Twiggy became uncomfortable and started to fidget. I paused and asked myself why was Twiggy doing this. Then I realized that this question, though intended for good, started to put limitations on the team.
At first, everyone was estatic in wanting to make a 10 hour game. I could see the gears turning with ideas and the excitement in their faces. We want this game to be great. By meeting this 10 hour quota we would be following the footsteps of many AAA titles (triple A). But by asking this question, did it do more harm than good? Was it a good requirement?
Today's standard in the video game industry is for AAA to achieve 10 hours of campaign gameplay, minimum. This 10 hours is based on the average gamers play through. Many gamers won't purchase a game unless it has 10 hours of playtime. Even if it receives awesome reviews, if it clocks at 8 hours, many will let it sit on the store shelves.
A lot of this reason comes down to the price/time investment. Back in the days of the PS2 and Xbox, the standard was around 15-20 hours. With the jump to next generation, production times stayed the same but player expectations went up. Players demanded better looking, physics driven, and realistic titles. With every demand there is a trade off. The trade off was less playtime. Some games are extending this with a multiplayer component, but I am not considering this feature as I am focusing on the campaign.
By asking this question, I put more requirement on completing a 10 hour game than focusing on gameplay. One of the questions that Will asks whenever he sees a feature of a game is "What does this do for the player?" Nothing except for a 10 hour game. Given that we are releasing a  free game, we don't have to worry as much about meeting this requirement. We just want a good game.