Why do you expect average Americans to understand what the war is? Last time they experienced war on their own territory was in 1860s. Since then all they know about war comes from books, movies and computer games. They view war as a great adventure they can practise target shooting.
I wouldn't say that's because they're American, they too have living WW II veterans, and from such slaughter fields like Anzio, Normandy or Ardennes. It's just the stereotypical American, that knows the war from games, just like stereotypical Pole is drunken car steeler.
Most of the (relatively) young people throughout the world view the war through the scope of Call Of Duty, for example lots of young Poles want to serve in the army and go to Afghanistan, because they think "it's like Black Hawk Down".
People from the West sometimes have only this "problem", that they do not necessarily understand the reality of Central/Eastern Europe, and how we roll here. From Western point of view the Warsaw Uprising logically could make sense, even if lost. But east of Oder river lies different world, and our country is a trap for both Eastern and Western Europeans when it comes to look at cultural/political/historical issues - a trap because a Poland is a borderland and is both Western and Eastern, so people "left" and "right" of us often make a mistake that everything here goes "left" or "right".
This aside, many people do not understand that Stalin would rather die, than help Poles, because Poles humiliated Stalin in Lenin's eyes in 1920, which thing he never forgot, and that II Polish Republic was a dam for Red Army to go West. Everything that could stop again USSR was burried in forests of Russia, under German occupation, in the atmosphere or in Warsaw. Why should Stalin attack the city if he could mantain his reserves and exterminate thousands of Polish youth an intelligence with German arms?
The Warsaw Uprising had one point - to throw out Germans by Polish army and welcome Soviets as they were guests of independent Polish liberators of souvereign capital city. But what popular books do not mention is that Warsaw wasn't the first city liberated (or tried to be liberated in this case) by AK (Polish Home Army) during the action "Burza" ("Storm") - and that's because in those other liberated by AK cities soldiers welcoming Red Army were disarmed, put to jail or executed as partisan units, because there can be only one liberator and it's USSR. Warsaw would be just one more city witnessing those scenes.
Everyone from the HQ knew what was happening east of Warsaw, and many officially protested and prohibited any further uprising action. Still, it began. Some of the people responsible for it were later explaining that it was "too late" to stop the machine, so they had an idea what terrible thing happened.
The esteem that Warsaw Uprising has in Poland is that it became an icon of martyrdom. Why? Because post-communists would rather make Poles martyrs than victors. So you have whole books, programs, interviews about this tragedy, yet when it's anniversary of Monte Cassino, Tobruk, Falaise, Battle for England, Narvik, or even Arnhem rescue operation, where Poles were if not decisive, then played major role, everything's silent.
That's how things go here. Western logic has nothing to do with this.