I never really understood the Vietnam War comparisons either. The Vietcong had guns, vehicles, and supply lines that kept them going for years. While the US still had a technological advantage, the Vietcong were still within the ballpark.
By contrast, the Ewoks had some dumbass spears, bows & arrows, and rocks against the Emperor's "best legion of troops" that had armor, laser weapons, and heavily armed walkers. The Ewoks should've been utterly annihilated, and the fact that they won in spite of being so hilariously outclassed had forever painted the stormtroopers as complete jokes.
Really, the Vietnam War and the Battle of Endor are night and day.