If I were going for postcount, this could probably be multiple (unrelated: initially typo'd "multiple" to "mule pile")
Point the first: some decent background music for SF ground combat. Gave me the "tech-heavy military SF" itch again.
Which OGRE sort of fills but also sort of doesn't. The only design is in defense force composition, which while still an open problem is a very different animal from Starmada, Battletech, or Traveller-type design. One thing I will say for OGRE though is that it handles attrition nicely - as soon as one side can't take an action, the game is over. The nature of the battle between implacable machine and humans making a last stand mean that morale is immaterial, so you have neither forced actions ("failed morale, must retreat towards map edge") nor denied actions ("pinned, can't fire this turn"). In this way, it avoids complexity.
Admittedly, a lot of wargames ignore morale effects, but it's nice to have a reasonable excuse. Should find more wargames with war machines and slavering aliens born to die ("this for the swarm!"), and I guess human troops either heroic, desperate, or hopped up on combat stimulants. Maybe that's part of why 40k is popular; they have morale rules, but they're not nearly as central to gameplay as in (say) Stargrunt, and plenty of things basically ignore them.
Also wargames are problematic because of scalability (often hard for 4-5 players at once to play with quick turn lengths), tendency to minmax in competitive environments, and somebody always loses. These are things which RPGs handle relatively well. Do people play wargames in the 3+ vs 1 "coalition of players and a referee in non-competitive campaign" mode?