Lets see here..
1. Couldn't see shit.. I hate obscure crap like that
2. No reason to be diving with red flares except for cinematic effect.. ugh
3. Didn't see the monster except for a bit through fog at the very end
4. Why is everyone fawning over this? There was nothing definitive to like because it was a poorly lit foggy preview with no acting or any redeeming anything.
Given that:
a) it's night
b) it's smoky
c) it's cloudy
4) it's a monster, not an enemy force
5) it's a monster movie
flares for a HALO jump, and the HALO jump in general, are actually somewhat in line. They would appear to be a highly-trained unit - I have a feeling there is more to what they are doing, as opposed to jumping in to fight the monster. They have wimpy firearms (I'm assuming, considering they are limited to what they are carrying on person) going up against a juggernaut the size of skyscrapers... they are probably trying to escort scientists or some politically-important type(s) to safety. Get them in fast and hot, so they can do the mission faster.
Just guessing, probably far off base. However, the big point about the flares is, while not tactically intelligent and probably not common during actual HALO missions (against human threats, mind you), perhaps there's a certain movie logic that actually allows this to make sense: it's dark and smoky with limited distant vision, and all the fire probably makes IR/night vision sort of useless - the flares allow them to keep each other in sight through the thick smoke, and they probably are far less worried about the giant lizard understanding and attacking the falling objects on fire.
Also - it's a damn movie.
Also, they get creative license because actual tactical accuracy tends to be frowned upon by the military if they try and show true military, as opposed to creative sci-fi non-existent armies or anything.
this is just a teaser trailer.
Also, this.
Also - as someone who tends to carefully look at details, cinematography, dialogue, acting, actual scenes playing out, the on-screen logic and plot and whatnot - a lot can be said in very little time. You can't make a teaser of an absolutely shit-tastic movie actually appear to be pure gold. You can, at best, make a terrible movie look "watchable" - but not epic. Too many things will be apparent, just from the mannerisms or cinematography, or from the way a teaser scene fully plays out, that gives a strong indication of true potential for any true fan of cinematography.
If you don't really pay much attention to actual production values, don't connect directors or writers to quality potential, and really ignore most of the movie creation process... and ultimately only consume movies for the entertainment... I can see how that isn't apparent.
Or, if low or high expectations of a movie's quality comes from how close to pure realism it is, which... uh, hate to remind anyone who missed it, but there's a giant fucking lizard roaming around (one who MIGHT just spit fire/lasers). Please suspend all disbelief.

Granted, it's nice to see a realistic approach to an unrealistic situation, and that's exactly what I am hoping to see out of this movie and, from what I've seen, there appears to be some chance of that. Even if the approach isn't politically realistic, I am sure it will be an enjoyable ride, one that absolutely trumps the last Hollywood Godzilla flick (which wasn't terrible at all, I enjoyed it).