Moscow in 1941 was much more important than in was in 1812, for one simple reason - railroads. Moscow was THE hub of the entire Soviet rail network. See
this map for illustration. Without Moscow, Soviet transportation capabilities would have been crippled, or at least badly hobbled.
That said, even if the Germans had launched
Barbarossa earlier, I don't think they would have taken Moscow before their attack ran out of steam. The biggest reason is distance and logistics. In an earlier post in this thread, I noted that the German objective for
Barbarossa was to destroy the Red Army west of the Dvina-Dniepr river line. This was suspiciously close to where German logistics planners identified as the limit of advance before the
Wehrmacht would have to come to an operational pause, resupply, reorganize, and generally get their sh*t together before they could advance further. (This is also probably why the battle of Smolensk was as long and nasty as it was - the Germans were pretty much at the end of their rope, logistics-wise, and the Soviets took advantage to launch a series of (extremely costly) counter attacks.)
Railroads were the key to transport in the USSR. The roads were crap, mostly unpaved, and you really don't want to be moving supplies by truck (and the Germans had a serious shortage of trucks anyway) over those kinds of distances. The fact that Soviet/Russian railroads were a wider gauge than western Europe is well known. One additional complication that I didn't know about until recently was that the distances between water and coal stations in the USSR was also greater than in western Europe. So German locomotives would run out of coal and water unless more stations were built. The Germans had counted on capturing Soviet locomotives and rolling stock, but the Soviets either moved them east or destroyed them. So not only did the Germans have to fix the tracks, they had to build more water and coal stops as well before they could use the railroads.
Some argue that Hitler should have kept Army Group Center driving on Moscow, instead of turning it south to help Army Group South destroy the Red Army forces in Ukraine. The problem with that is it would leave Army Group Center with an enormously long exposed flank, protected only by thinly stretched, foot-mobile infantry units, with very large Red Army forces in Ukraine. And even as they were being driven back, one thing the Red Army had shown a marked propensity for was launching counterattacks, even if they were extremely costly. If the Soviet Forces in Ukraine had attacked north into that exposed flank, they could put the supply lines for Army Group Center in jeopardy, and thus pose a dire threat to Army Group Center itself.
The other thing is, even when Army Group Center resumed its advance toward Moscow in Operation
Typhoon (the fact that this is a separate named operation is, by itself, an acknowledgement that
Barbarossa failed to meet its objectives), the German army was badly beat up and its units were significantly understrength in both men and equipment. They might have gotten closer to Moscow before the
rasputitza halted them, but they still wouldn't have gotten there. And the mud didn't stop the Russians from bringing reinforcements, because mud doesn't bother railroads.
My favorite summary comes from historian David Glantz*. To paraphrase,
"Moscow determined it would be a long war; Stalingrad determined that Germany would lose that war; and Kursk determined that that defeat would be total."*I highly recommend Glantz's book,
When Titans Clashed, written with Jonathan House.