I could be talking out of my ass here, but I think Zastels main gripe is that UE4 doesn't have an "internal" grid, like Hammer or older engines used to have, meaning, if you fall out of the grid you can snap back easily. This is also the reason why I prefer Maya much more than 3ds max. In Maya if you hold X and move a component in any direction it snaps to the nearest grid step, doesn't matter which direction, Maya always "knows" where the next grid step is, whereas in Max, you need to snap to the grid drawn on the viewport, meaning, instead of snapping the component to an internal grid, 3dsmax "looks" at the viewport and snaps the component to the nearest grid point your cursor is pointing. This means that you can't really snap vertically in the perspective viewport, because the grid plane in that one is 2d (only X and Y), you can't snap if the grid is too small and sometimes you can't snap at all because of the angle your viewport is. Again, I could be talking out of my ass because I didn't program these tools, but at least that's the impression I get when working with them.
Unreal 4 could benefit greatly from a feature we have on the Overwatch editor: A hotkey to snap a selection to the pivot of another object, this way you can at least put a piece back on the same grid as the rest (so you don't end up with pieces in different grids, sometimes this is OK, but sometimes these tiny gaps drive me crazy).
Zastel, you should post your feedback on the Epic forum, maybe they will listen if a lot of people bring it up. I'm pretty sure I posted the same thing there at some point.