Windows lost the taskbar in Win 7, OS X has never had one.

In my experience a dock is preferable when you have a small number of windows open for each application and a taskbar is preferable with a larger number. Perhaps tabbed applications have made this switch possible.

Don't know about Win7, but Win8 has one. You just have to disable the "combine" setting and you have a taskbar with one entry per window.

It's the same in Windows 7. You can also make the icons smaller and enable text labels for an authentic Windows Vista experience ;)