I have mine on auto-hide. It's been like that ever seen my Dad built my first computer. I keep it there out have habit, but it doesnt bother me to have it up.
Auto-hide is useful for keeping naughty minimized windows undiscovered by room intruders.
Alt-tab doesn't work when you're running things which don't have a window, nor does it help with things like connection status monitors which attach to the taskbar. Plus it's a lot easier to create shell shortcuts and place them on the taskbar to run something than having to open a command prompt and pass the switches to the exe whenever you want to open it.