I believe it would be plain wrong to think that developers working at large studios don't have a passion for what they are doing. They most certainly do. But their job involves so many different parameters. They need to plan everything in advance, make sure all deadlines are met, include or cut away features according to the requests of management, write reports, deal with quite a bit of corporate bureaucracy, etc, etc... It's completely different from working in your garage at your own pace. Of course their way has its own advantages too, in that everyone does whatever he or she's good at and doesn't need to worry about the rest.