Probably not. The more I think about it, FullScreen Mode seems to be a solution to a problem that nobody actually had.
Were people really having problems with focusing on a program because they can see another program is hiding behind the window? Was there really an outcry for the multitasking personal computer to look like a single tasking tablet? Is seeing the clock really hurting productivity?
Sure, people now claim that FullScreen mode increases their productivity but I highly doubt these people would be unproductive if it never existed. I kinda view it like the hype behind Disney's Cars Land. Nobody EVER said they wanted to visit Radiator Springs but now that it exists then suddenly people act as if it's what they always wanted. (But in reality we just want a Star Wars or Marvel based land.)