currently I find myself replacing almost every window that is not maximized, after it is opened. Because the window placement algorithm is only looking for a free spot. This often leeds to two windows almost next to each other but some pixels apart, or sometimes one even sits a bit lower than the other.
Or a window is placed near a screen border but does not snap to it.
But what I did notice is that the space between two windows or a window and a screen border is very close in these cases and just clicking it and moving it one stap snaps them together.
So I think that running the snapping after placing a window (not enforced but optional, I don't know maybe some people prefer the way it currently is) would already be sufficient to eliminate almost every if not every single one of these cases :-)
I hope that's not too a big change.
Duplicate of bug 5785.