Really? If that's what you think, then you don't know the military as well as you let on. Not by a long shot.
You seem to be under the mistaken impression that taking something seriously means being devoid of humor or levity. They needn't be mutually exclusive, and as others have stated, go hand in hand in some pretty bad situations; more often than you apparently think, for that matter.
My take on this whole 'humor vs drama' or 'light vs dark' debate is that fans are looking at this from the wrong angles. Far too many people, especially lately, scrutinize humor while passively accepting (melo)drama, no matter how heavy handed it may be. This is unquestionably the general mood of the fan community by now; the very existence of threads like this is a testament to that. I'm starting to wonder when we'll see threads asking how much drama a film should have. Seems that people have completely forgotten what melodrama is; I'm surprised that soap operas aren't all the rage these days. Melodrama, to me, is every bit as obnoxious as the most brainless slapstick humor I could imagine; I take one about as seriously as I take the other. I see it in the threads for prospective/upcoming films all the time; the first thing fans beg for in a movie nowadays is a 'dour, dramatic, serious tone with NO KIDDY COMEDY'. The ironic thing is that much of the humor in these Marvel films has been referential in nature, referencing things that most kids and even young adults either aren't familiar with or wouldn't understand.
I'm getting off track here, but my point is that pitting one against the other is a fool's errand, and for several reasons. First of all, there's no reason why they can't coexist and complement one another, and if you're old enough to walk and talk, I shouldn't need to provide examples of this; hundreds of movies have done it before. Secondly, and this is the most important, is that you dismiss context when you're asking for how much humor you want to see in a film. 'How much' is completely arbitrary, when what you should be concerned with is the context and quality of the humor; i.e. whether or not it fits the character(s), the relevance, delivery, setup, paradox, etc. The last piece is one that I find especially disturbing, in that when someone dismisses humor in favor of drama, what they're essentially saying is that drama/seriousness is a free ticket to quality, while humor is inherently substandard. I can't abide that nonsense. No disrespect to the OP or anything, but I feel as if this thread, and the myriad of others like it, is fundamentally asking the wrong questions. I can't understand why an arbitrary amount of humor is more important to some folks than the performances, characterizations, cinematography, dialogue, and a whole host of other things that have a much greater impact on the final product.