I think that the very issue raised here is the reason why the West was ultimately important. Both sides placed large amounts of resources into the East, and it was deemed immesnley important. But because for the better part of three years, neither side was able to substantially alter the strategic picture in that area (it took Grant into 1865 to gain a strategic victory in the area), it became the west that determined the the fate of the Union and Confederacy.
Now it isn't really as simple as that, as its very easy to see that Grant's attrition policy is what won the East and brought the Confederacy down. The game actually models this quite well, although it doesn't allow people the "glory" of vast offensive and defensive campaigns in the Eastern theatre. Indeed, most of my eastern strategy consist entirely of stacking about 80,000 men under one of my better generals in Fredericksburg and letting the Union bleed against that for three+ years. But I think the problem for many, is that this strategy isn't very "sexy".
The way to solve this isn't to decrease the importance of the West, but rather break-up the north-eastern Virginia cooridor alittle bit more. I also think that offensive manuevers shouldn't be as punishing as they are. I am not sure if its the difficulty I play, or the nature of the game in general, but the attacker seems to be at a severe disadvantage to the defender. I can see this if the defending army has been in a province for longer that 1 turn (some sort of pseudo entrenchment bonus), but it seems that attacking units route much quicker than defending units et ceteris paribus. I am ok with attacking forces having more casualties, but I am not sure that a "defensive stance" really generated a significant morale advantage. I would be willing to argue the opposite. An attacker will have the advantage of being able to have the resources in place to rally units at critical areas of attack much more so than a defender. But I am digressing at this point.
Ultimately, decreasing the "attacking penalty" and giving more room for army manuevers in the north-eastern part of Virgina would make the situation much more fluid there. While it may not alter the result in any game, it would certainly make it feel more fun in that region, other than another "oh boy, a 150k plus Union army is about to attack my 80k army and get the crap kicked out of it again". In essence, the game models the eastern theatre as it was Grant's attrition model the entire time (as the only real danger to the Confederacy there is whether you can replenish your battle losses quickly enough to not be forced to retreat), rather than the Napoleonic "war of manuever" that existed there until Grant assumed command.