Why the taskbar must be on the side:
Any serious text document I work on, or code, will stretch beyond the bottom of my screen. If you take away from the vertical real estate, I'll waste more time scrolling to find the relevant part of the text.
For quite some time, MS tried to steal my productivity by reducing useful vertical screen space: taskbar, window titles, menu bars, ribbons, status bar .... it's quite ridiculous.
I guess it's all right for watching youtube.