The game sucked....
I just imagine that the 4th dimension is another direction in which we can't go.
Look at a 2D environment. Things that 'live' there, can only move in 2 directions. Sometimes they have to take a long walk around because something's in the way.

If they could move in the 3rd dimension, they could take a shortcut.
If we could use they 4th dimension, travelling could be faster.
Edit: ehm... no humor intended Rndm...
