OS X :: Why No Snap To Screen Edge Like Win7

With OS X, I always find it annoying that windows can still me moved when maximized. I don't see the point of this since 99% of the problem this causes is that my windows are offset by 2-5 pixels (which I then have to zoom, then re-zoom to maximize the window again). Why can't we have snapping to window edges? Many programs already do this, and they don't detract from the design purity of OS X (unlike Windows 7 which does this over the top and fugly screen edge animation). A slight nudge when your window hits 2-4pxs off the side of the screen would suffice. A center line should exist too, since I find myself using my screen very much so half and half - it is very annoying to get the windows to be half and half equally.