Re: OK, let me get this straight..
In a perfect world yes. Only it's not a perfect world. You might have everything running well in Linux bar one bit of closed abandoned horror. Wine gives you a possible get out jail free card.
The other thing Wine excels at is being great reference source when MSDN leaves you scratching your head. The C source is well written and much clearer than the pirate Windows 2000 C/C++ (as in neither language) source you can find on the internet.
The problem is that people think Wine means you can just run all Windows software, and that is just too much to ask. Windows can't do that either. There was an interesting project a few years ago, Wine on Windows, as Wine is better for running old Windows software than Windows, but it seams abandoned now.
But ideally, yes, you don't need Wine.