But it allows for an 80+ man engagements and ~4km visual distance on my 3 year old computer. I'd say I'm happy enough with the graphics.
You must have baught one hell of a computer back then. Of course there are explanations for the sluggish performance. The reasons you mentioned and faulty optimization being only a few of them, while the latter is getting better from patch to patch.
I'm not saying the graphics are bad and even if they were, what choice do you have, really? If you want to play that kind of game you can only chose between Operation Flashpoint and Armed Assault. Both lack in the optimization department and OFP looks really really dated by todays standards, still they are a one-of-a-kind.
My golden rule of graphics: Graphics only need to be as good as they need to be to immerse you.
According to that even OFP's graphics qualify as good enough. How could ArmA's possibly fail?
I just feel strange whenever I see people drool over high-res screenshots with maxed out details, full AA and AF that would require an Alien sci-fi pc to run half-smooth.
You can see what computers are able to do if you go to the theater and watch a movie. 300 for example, Lord of the Rings or The Matrix. Its just that those movie-effects aren't rendered in real-time and if you look at some of the screenshots of ArmA you could say (with a satirical note of course) they aren't either.
Before a game can claim to have good graphics it has to prove that the performance is good too (relative to the graphics) and in this relation ArmA is just mediocre in my personal opinion.