The monotony of the fronts, esp. Western, doesn’t bother me either in this game. I would like to have seen more development of a railroad/strategic movement capability for non-combat movment and forts (i.e. sieges that require a diversion away from the “attack 'o stacks” and control certain elements of attack, movement, etc.). Static front lines are just a characteristic of the time, but countries like Germany should have been able to benefit from a superior rail system (and interior comm lines). Other countries like Russia should not be rewarded for having a comparably inferior one. The Allies, of course, benefit from near total command of the oceans; they go where and when they want to.
But alas, this is where house rules come in, and I’ve seen some pretty creative ones so far. The PTR were a good start.