"I'd rather say 'no' to a good deal, than 'yes' to one that craters." There is more to having a successful project than simply abiding by the specific terms of a contract. You can do everything right, go above and beyond what is expected, and yet still have the project devolve into a stinking mess. Understanding the full scope not just of your work, but also the whole project is vital for you to be able to know that your work will be something to be proud of. Many technology professionals are short sighted and see only the profit margin on the current contract, and don't fully think through what the loss of respect will cost them over the length of their career.