I guess i'm in the minority then, I just felt like having guns mowing down tens/hundreds of Aliens was whittling down the numbers to something they had a chance, no matter how slight, of fighting back against.
I still like the scenes though
Exactly, but it's a false hope. The marines (and the audience) knows it, but it introduces a little bit of doubt. It's all part of ramping up the premise. In Alien, it's one xenomorph, playing cat and mouse against a small, ill-prepared crew, so it's sci-fi horror. In the beginning, the crew thinks they are hunting the alien, but as the film unrolls, it turns out the alien is hunting the crew.
In Aliens, Cameron was clever to turn it into a sci-fi action-horror film. The Marines are professional soldiers, trained and equipped to the gills, and instead of an easy "bug hunt", they get a swarm of monstrous, aggressive xenomorphs who don't just want to kill them, they want to imprison them, lay eggs inside them, and then kill them as the alien progeny hatches out of them. The crew from the Nostromo gets ramped up into a squad of Marines, so the aliens get ramped up into swarm of hungry monsters to keep the conflict level.
The last half hour is almost a separate add-on, where the Alien Queen is introduced, and Ripley goes one-on-one with her, (harking back to the first film), but again with the combatants raised to a higher level of baddassery in the form of Ripley in a loader exo-skeleton vs the huge Alien Queen.
It works so well because as a film because it's being more than just a copy of the first film, while managing to include and expand on the important elements from the first film.