In Windows everything really wants to take up the whole screen. If you drag a window near an edge, it'll try and maximize! If you double click, it maxmizes! If you click the button, it maximizes! Shoot, in Windows 8 they wanted everything to start in full screen with that modern UI.

As much as I love overlapping and reasonably sized windows and having many windows strewn about my very large monitor, I'll see a post on Reddit about how websites aren't designed to look good when maximized on a 21:9 monitor, and then I'll face palm. It's weird.