‘Sinners’ Producer Says Costumes Were Purchased From Marvel’s ‘Blade’ Reboot That ‘Ended Up Not Shooting’: They Had a ‘Warehouse Full of Period-Appropriate Clothes’
You'll note that's literally a twenty year old forum thread.
Apparently it's because the movie was one of the last real sci-fi movies done practically instead of with copy and paste CGI, and so they're one of the last sets of armor you could fit a squad of sci-fi goons with.