Robin Williams's 'Good Morning, Vietnam' - More Than Just Jokes?

Okay, so I just rewatched 'Good Morning, Vietnam' and man, Robin Williams was on another level. But I think there's more to it than just his crazy improv and the killer soundtrack. What always gets me is how the film shifts in tone. You've got the pure comedy gold at the radio station, those insane broadcasts that totally ruffle the feathers of Lt. Hauk (Bruno Kirby, perfect as the stick-in-the-mud). But then, bam, the film throws in these moments of real gut-wrenching reality, especially towards the end when Adrian Cronauer actually sees the war's impact and his optimism is challenged. I think the director -- was it Levinson? -- really nailed the structure. It's a smart way to slowly peel back the layers. At first you're laughing, thinking this is just a fish-out-of-water comedy. But then the film subtly introduces the darker side, the political tensions, the anti-American feelings, the raw cost of conflict. The bombing scene in Saigon is a turning point, no question. It completely changes Cronauer and his perspective. Here's my crazy theory: 'Good Morning, Vietnam' is secretly a pretty brilliant character study disguised as a comedy. It basically uses Williams' comedic persona as bait to draw you in, then sucker punches you with some serious emotional weight. It's about how even the most optimistic, hilarious person can be confronted with realities that change them forever. It's a little uneven at times, and the romance subplot feels kinda tacked on, but overall it's a really effective film. What are your thoughts? Did anyone else get sucker-punched by the tonal shift like I did? And one more thing, i remember watching this as a kid and thinking it was just hilarious but as an adult you start thinking about the real situation and the war and how it really impacted these people.