I find that one of the best things about OSX.. the fact that applications can't monopolise the user's focus. It *really* annoys me that every application and it's dog in windows believes that it has the sole right to create a modal dialogue window.
To each his own, but I find i tend to give programs i'm using my focus by default. I can't give a program focus if I don't know it even exists!
The option to have one couldn't be a bad thing. I hope the PC/Mac problem swallows it's pride to give us the best bits from each interface sooner rather than later.