One statement covers all the above.
It's 4-5 years into a global war which turned nuclear 2 1/2 years before.
Divisions with a full strength of roughly ten thousand men and several hundred MBTs are now lucky to number a third of that in manpower and are likely to possess barely enough tanks to deploy a short company.
Nuclear weapons are not just targeted at cities. They were also aimed at factory complexes, transportation hubs, mining centres, and I'd be supprised if even agricultural capacity wasn't a factor in some of the larger nukes (even just at assessing the fallout zones). Note also troop concentrations were also targeted regularly with some divisions effectively wiped out.
Why wouldn't warships also be targeted? Some of them have crews numbering in the thousands and they're certainly not spread out the way a division is.
Airfields, even roadways capable of landing aircraft on would also be viable targets once restraint had given way to desperation. The planes themselves might be more than capable while in the air, but if they've got nowhere to land, and nobody left to service them once they're there.....
Supply of essential parts, munitions and fuel has been mentioned on many occasions both by the writers and players/GMs. Take the Krakow helicopter as another example - the machine is in perfect working order, but ammunition supply is limited to little more than it flew in with and fuel amounts to just a few hundred litres - maybe an hour or two of flight time. I'm almost certian theres plenty more aircraft out there, grounded for the very same reasons.
Shorthanded as they are (1000 men) the US 8th ID possesses an OH58, two Blackhawks and an Apache, all grounded (most of the time) by lack of fuel (and parts for at least one of the Blackhawks) but still so valuable as to be dragged around Europe by the Division on trucks.
The 2nd MARDIV likewise possesses at least one CV-22 Osprey based on the USS Tarawa (Plate C1, Nautical/Aviation Handbook). This reference also implies (along with the reference to the USS John Hancock in Going Home) that there is still at least some naval capacity (mostly likely heavily damaged from the aformentioned nukes and conventional attacks) but limited once again by lack of fuel, munitions and spare parts.
With regard to a marine division not deploying alone, the 2nd Marines in the spring offensive certainly did not! They were a part of a MUCH larger operation which involved the forces of at least four countries (the US, Germany, Canada and Denmark - the British possibly as I have written previously) with wide reaching aims. The 2nd Marines were also the only NATO marine force in Europe (besides the 500 strong UK 1st Royal Marine Brigade in Norway) and therefore the only unit capable of fulfilling the task of "launching amphibious assaults against the Polish Baltic Coast and across the estuary of the Vistula".
I would also point out that the divsion, listed on the 1st of July 2000 at a strength of 4000 men, is far stronger than the real life US 13th Marine Expeditionary Unit
http://en.wikipedia.org/wiki/13th_Ma...ditionary_Unit with only approximately 2,200 men. I'm fairly certain there's plenty of support personel amongst the 4000 of the 2nd Marines and as mentioned above, air support is likely to be virtually nonexistant for all sides by that stage of the war. The Osprey above may in fact have been the only operational aircraft of any type within several hundred miles and reserved purely for emergencies (URGENT casualty evacuation for example).
Now the point I think most people tend to forget is units even of divisional size do not act without orders from above. Other divisions within the Corp undoubtably have their own missons, sometimes in support of each other, sometimes seperate, but there is almost always a guiding hand at the Corp or Army level.
Take the Allied operations in Europe in 1944-45. Eisenhower was in overall command of all allied forces with Patton and Montgomery in command of seperate armies consisting of a number of divisions. Breaking it down further and using Operation Market Garden as an example, we see individual divisions, all operating within a relatively narrow corridor, tasked with individual objectives, some of which were acheived, others which were not (the British Airborne at Arnhem springs to mind).
Therefore, I believe the only way possible to justify the presence of the US 5th ID at Lodz is if you take a step back and look at the big picture. Even just stepping back to the Corp level isn't far enough though - it only begins to make sense when you look at the European theatre as a whole and consider that the 5th ID was just the spearhead of a drive designed to force the Pact armies to withdraw and secure their lines of supply and communication (limited as they were by 2000).
Individual objectives such as securing coal fields would be simply a side benefit of the overall offensive.