I’d actually say the style is more like Iron Man.
I can see Gundam somewhat, but not really Lego (I used to love those and Bionicles) or Power Rangers.
Alien is something I see more in the design of the Marines, the Elites and the Flood, though I also see Predator for the Elites.
The only other thing I’d consider close is Mega Man (Proto Man seems to be wearing a motorcycle helmet, and the designs in X are similar to the Spartan armors in some ways).
I like it, but a lot of somewhat simple designs are still good from decades ago, even centuries and millennia ago.
I don’t think you can argue that.
Generic means there are a lot of similar designs.
Halo 4 was where things started to look worse for the armors.
Halo Infinite for you new players, is a return to classic Halo artstyle, instead of them just taking liberties and trying to finesse the classic aesthetics.