If you wanted a dock aka icon based taskbar on Gnome, there were plenty of options before Unity came around. Out of the box they all work pretty much the same. They remain good alternatives if you want to customise. I used to use AWN, worked fine, but I'm fairly happy with Unity. It works very well for window management, and that's really all I want from a dock.
I think the old-school task bar is potentially more useful because it lets you see the window titles at one glance. But it just doesn't scale well beyond a dozen or so windows, either all the text is elided or you end up grouping windows by program at which point you might as well use a dock.
Not only that but there are plenty of options that are still better than Unity. Well, the newest Unity is even good enough for me to leave as default on my non-main machine. Cairo-dock, Docky and Plank (Docky's less functional successor) are all more configurable than Unity and more similar to what people expect from Windows 7 and OS X.
I think the old-school task bar is potentially more useful because it lets you see the window titles at one glance. But it just doesn't scale well beyond a dozen or so windows, either all the text is elided or you end up grouping windows by program at which point you might as well use a dock.