- The military is depicted as quite functional and competent, with leaders even acknowledging failure. We know now that this just doesn't happen
- Some of the military heroics come across more as sincere than ironic, with Rico forming a genuine bond with his mates and high-ranking officers giving him genuine respect
- The bugs are shown to be a genuine threat to humanity when they wipe out Buenos Aires, raising the question of "well what are they supposed to do?"
Responding to some of the points here:
-I don't know if "competent" is the word I'd use to describe the Federation's military in this film. First Klendathu is a FUBAR. They have other victories, but even discounting that the "victory" at the end of film 1 is revealed to be nothing of the sort in Marauder, are they competent? The Mobile Infantry seems to be composed of nothing but infantry, with no armour or artillery to support them. Their armour is grossly ineffective against the Arachnids, their weapons aren't much better.
-On the subject of acknowledging failures, that's technically true, but there's a case to be made that the events of the first film are taking place as in-universe propaganda. As in, the events are literally true, but it's presented as a propo piece (see the start and end). In that context, viewing it in this sense, the Federation can acknowledge a defeat, as long as that defeat leads to the climax of a victory (capture of the brain bug). Also, this is kind of fanwank, but if you look at the five ST films, the Federation gets more dictorial as time goes on, so while we know the Federation was pretty corrupt before the First Bug War (see the prequel comics), the Federation's relative openness here can be excused in the context of how deceptive things get. Even by ST2, the Federation is outright lying to its citizens.
-"The Federation is a fascist empire. The Bugs are an existential threat to humanity." These aren't mutually exclusive statements.
I think you make a fair point, but again, without delving into events prior to the film, even in the film's context by itself, there's a wink-nudge element towards the Bugs' strike. We're told that "Mormon extremists" (what?) tried to settle an Arachnid-controlled world, and we see the students cut open Arachnid bodies in science classes, so clearly they got those bodies from somewhere. While there's a happy middle ground between "let the humans roll over us" and "let's wipe out the human race," the implication, if one chooses to see it, is that the Bugs are reacting to human aggression.
I regards to the destruction of Buenes Aires, it being a meteor I'd say questions how much of a direct attack this actually was. The result was catastrophic, but it was just a meteor, not a missle or a nuke. The fact that Earth sees this is a direct attack, which was likely just a random meteor knocked out of orbit, and are so willing to immediately want to wipe the Bugs out, when the only other interaction has been humans trying to establish colonies on their planet, speaks more to how this militaristic society sees itself as the centre of everything, and that any bad thing that happens to them must therefor be due to malicious intent.
A meteor would be, on average, much more devastating than a nuke, given its size. A 7 mile wide meteor caused the KT extinction - even reducing that mass by a few miles would still inflict catastrophic damage. There's a reason why mass-driver weapons are portrayed as so devasting in sci-fi for instance, because the laws of physics demonstrate that they would be.
However, it's pretty certain that the meteor was indeed fired by the Arachnids. People have long speculated it's a false flag, but that really doesn't hold up to scrutiny. Even entirely within the film's context and nothing else, it's established as soon as the meteor misses the ship that it came out of the AQZ. So unless Zander and/or the captain are in on a false flag op (and there's nothing to suggest they are), it's pretty certain that in this case, the Bug attack is genuine.