Frankly, the only reason I don't broach modern military RP's as a genre isn't because they're niche. The Last Bastion is a post apocalypse sci-fi hybrid, that's pretty niche, and yet it's successful anyway.

No, the reason I don't tackle modern military RP's is because people have absolutely no idea what they're doing. Please let me explain before someone calls me an elitist bastard. (Though I totally am.)

Military RP's in my opinion have a barrier to entry if you want to play them even somewhat realistically: An understanding of military strategy and tactics, from the individual level to the platoon level. For example: Tanks are the front line, infantry play the support role, proper reconnaissance and air superiority wins nearly everything, and ninety percent of your time is spent being on edge of being shot at in civilian areas rather than shooting at actual targets as you pass through streets and alleys and stumble on jittery civilians as scared as you. Hesitate and you die. Fire indiscriminately and you're a war criminal.

Simply put, military RP's if played correctly should be far more about unit tactics and psychological warfare, not about the actual combat, which would start and end as a series of rapid skirmishes. (As no modern military commander in their right mind throws all of their resources into one battle. Putting all your eggs in one basket is the sign of a man who sincerely thinks they can win a war in one battle.)

Now this is a little difficult, but not impossible, to write out as a GM. The issue is that unlike with other RP's I run, it would [b]require[/b] the players to understand basic military strategy. At least some rudimentary knowledge of the works of Sun Tzu, even, would be decent because it at least tells you the basic train of thought you should have. If we're talking strictly grunts fighting other grunts, then at least understand unit tactics and just how vulnerable you really are. (Flanking, cover, LoS, target identification, recon, calling for and responding to coms, realizing that one shot is all it takes to kill you, etc.)

Fact of the matter is?

The vast majority of people on this site do not meet these qualifications. If I were to make a military RP, I would have to dumb it down so hard that the point of it would be lost. It would turn into generic action RP with military flavouring, and that's just selling out. It would satisfy nobody looking for a true military RP.