Did you know that Mozilla has tabbed browsing? Of course you did. There are lots of people that use Mozilla's tabbed browsing. Or a similar such thing in another browser. But there are many people who don't, and can't figure out why tabs are so popular.
Well, whether you like them or not depends a lot on how you use your computer. If you're like me, you have 5 or 6 applications open at the same time. In general, I have a file manager-like window open, a mail window, an audio player in the corner, perhaps a few instant messaging windows scattered about, a few terminal/telnet sessions open, a text editor and some browser windows.
Now that means, on average I have 8 to 12 windows open at once. However, the taskbar, dock, or whatever, gets a little full at this point. It gets too inconvenient to use it as it involves a lot of searching around. So I pretty much stopped using it. Fortunately, I have a 19-inch monitor so I can see everything at once, so I don't need the taskbar. I know where the mail window is because it's always in the upper-right corner of the screen.
Having less windows on screen is convenient for me as it means I can see a tiny bit of every window at once. I need a text editor? I just click on that bit of blue covered up by a bunch of other windows. I know that since I've set my text editor up to have a blue background. I can use spatial memory and colour memory to know exactly where every window is on the screen. With tabbed browsing, I can lower the number of windows on screen and keep order to my desktop, since I know where the browser window is. Thus, it reduces the amount of time it takes to deal with other applications as there aren't 10 browser windows covering them.
However, there are some people that keep all their windows maximized. Do tabbed browsers have value there? Not really. In the case, the tab bar is just duplicating the taskbar.
If you only usually have three or four windows open at once, tabbed browsers aren't as useful for you either, since you can just see the list of windows on the taskbar.
Of course, I'm generalizing a bit, but each person can think of their own reasons for using tabs or not using them. The point is that if you don't like tabs, it probably has a lot more to do with the way that you use computer and organize your desktop (your desktop habits, if you will), than with any fault of tabbed browsing itself.